Would a Doctor or a Policeman participate in major crimes such as these?

[Kattrup]

So you accept that given the alleged actions of the killer in cutting a piece of the apron and then using it to either stem the blood from a cut or to wipe his hands or knife there would likely as not be blood stains on both sides of the piece?

As I have said previous folding would still involve the killer having to touch/handle and cut a piece of the apron with two bloody hands leaving traces of blood on both sides

For your information Dr Brown as quoted in The Times Inquest report: “On the piece brought on there were smears of blood on one side"

Oh dear, sounds like someone is quoting a newspaper. Aren’t those unsafe to rely on, Trevor? Seems a bit blinkered to me, relying on newspapers to prop up your old unaccepted “theories”

but since you insist, let’s have the full sentence:” On the piece of apron brought on there were smears of blood on one side as if a hand or a knife had been wiped on it”
Wow, so Eddowes wiped her hand or knife on this sizeable makeshift sanitary napkin? Your “theory” holds up so well to scrutiny, Trevor, doesn’t it just? No. I’m being sarcastic. It doesn’t.

[Kattrup]

Possibly, Kattrup, but I'd pose the following question.

How do we distinguish his familiarity from the victim's familiarity? In East London street prostitution, the woman leads the man; the man does not lead the woman.

Inspector Henry Moore:

"“What makes it so easy for him” – the inspector always referred to the murderer as “him” – “is that the women lead him, of their own free will, to the spot where they know interruption is least likely. It is not as if he had to wait for his chance; they make the chance for him."


In the general scheme of things, if a person traveling from point A to point B takes three times longer than expected it means he's slow; or that he has stopped somewhere along the way; or that he simply got lost.

But the idea that the Ripper was a man with great knowledge of the local geography has become such a popular part of the mythos of the case, that few care to entertain the third option.

Obviously there’s no way of knowing, as said I personally believe that he’d want a familiarity with the surroundings in order to strike with such impunity, but as we know it could very easily be the victims who led him to spots they persuaded him were secluded and safe.

I’m not aware that people are unwilling to discuss whether JtR had local knowledge, but perhaps I’ve missed your threads on the topic?

[Herlock Sholmes]

So you accept that given the alleged actions of the killer in cutting a piece of the apron and then using it to either stem the blood from a cut or to wipe his hands or knife there would likely as not be blood stains on both sides of the piece?

As I have said previous folding would still involve the killer having to touch/handle and cut a piece of the apron with two bloody hands leaving traces of blood on both sides

For your information Dr Brown as quoted in The Times Inquest report: “On the piece brought on there were smears of blood on one side"

www.trevormarriott.co.uk

You’re trying too hard to recreate the killers every minute move which is an impossibility. If you drop a piece of cloth on the floor then pick it up from near the centre with soiled hands you can easily use it and only soil the one side. The killer might have cut away the piece and dropped it on the floor next to him to pick up when he’d finished what he was doing. On finishing he picks it up and only soils one side. We can’t know exactly what he did and in what order so we can’t assume that something couldn’t be achieved.

He could just have used the cloth for cleaning the knife. Did he have blood on his hands? How can we know that he didn’t wear gloves to prevent this. I mentioned the possibility of the killer using gloves on the Chapman thread. I don’t see why this is impossible or even unlikely? Why couldn’t the killer have strangled his victim, taken a pair of gloves from his coat pocket and taken his coat off? He then mutilates, puts the stained gloves in his coat pocket then puts the coat back on to hide any bloodstains on his shirt/trousers.

[Trevor Marriott]

You’re trying too hard to recreate the killers every minute move which is an impossibility. If you drop a piece of cloth on the floor then pick it up from near the centre with soiled hands you can easily use it and only soil the one side. The killer might have cut away the piece and dropped it on the floor next to him to pick up when he’d finished what he was doing. On finishing he picks it up and only soils one side. We can’t know exactly what he did and in what order so we can’t assume that something couldn’t be achieved.

He could just have used the cloth for cleaning the knife. Did he have blood on his hands? How can we know that he didn’t wear gloves to prevent this. I mentioned the possibility of the killer using gloves on the Chapman thread. I don’t see why this is impossible or even unlikely? Why couldn’t the killer have strangled his victim, taken a pair of gloves from his coat pocket and taken his coat off? He then mutilates, puts the stained gloves in his coat pocket then puts the coat back on to hide any bloodstains on his shirt/trousers.

Oh come on what is this coming to the killer wearing gloves now

https://www.trevormarriott.co.uk

[JeffHamm]

Sorry Jeff, that's not how it works. Long said it wasn't there and he knew for certain it wasn't there (we do not know how he knew but the obvious implication would be that he did his duty and checked the doorway the first time round). (conversely, one might ask how did he manage to notice the apron the second time - precisely because it wasn't there the first).
You've no evidence that contradicts this, therefore his statement stands. For all witness statement we can speculate that he or she might have lied, might have been mistaken, might have been part of a conspiracy - however, without empirical basis, such speculation is invalid. It is of course still very common around here.

As I've mentioned some time ago, probability is not very relevant in history, because either something happened or it did not. Whether you personally think Long lying or being mistaken is more probable than JtR venturing out again after a kill is completely irrelevant.

Hi Kattrup,

I guess we see things differently. The notion that something happened or it didn't might be true, but we're one stepped removed from that. We have to interpret the information we have, and the information is incomplete so we cannot know if something happened or if it did not. Therefore, in all areas of research, we weigh the various theories by the probabilities. That is how research works, in all fields. In some fields the probabilities can be objectively calculated, in others they cannot. We can test probabilities by examining the follow on implications, meaning the predictions, and see if we can find evidence for or against those predictions.

And no, just because a witness says something doesn't mean their statements "stand as true", it just means it is true they said a particular thing. So it is true that PC Long said the apron wasn't there, but that doesn't mean the apron was there. We can assume he checked the stairwell, but making that assumption doesn't mean he actually did. We need to critically evaluate his testimony, as we do with most witnesses. We look for corroborating statements, and we have another more senior police office (Halse I think?) who points out that he passed by at 2:20 and says he might have missed it even if it was there. That statement tells us that it must be possible to have missed it, which is why we have to examine PC Long and whether or not it is reasonable to consider the possibility that he missed the apron.

I think it is, but you may think it is not. That's fine, we've just made a different interpretation on something where neither of us can truly know which is true.

Anyway, we clearly approach things from different perspectives, so if you feel that a witness can never be mistaken then we're likely to disagree on a number of points, and given our differences arise from different approaches to the data interpretation, it's unlikely either of us will change the other's view.

- Jeff

[Kattrup]

. Therefore, in all areas of research, we weigh the various theories by the probabilities. That is how research works, in all fields.

this is incorrect, but expected.Not all areas of research utilize probability.

Probability is not useful directly in analyzing historical sources.

But I perfectly agree: we approach the topic with different perspectives and that leads to disagreement. I’m an historian and you’re a statistician or similar. Our methodologies differ. Personally, I believe I’m on safer grounds since this case is a historical one and must be approached as such, but You’ll probably disagree

[JeffHamm]

Hi Jeff
I know I dont disagree with you much, but Im afraid I totally disagree with you here. Im even going to go so far as to say that you are wrong. Long didnt say he could have missed it, or he didnt think it was there. He said it wasnt there. There is no evidence he was wrong or lying, so we must go with his evidence. He could have missed it of course-but thats veering into speculation when there is no need to. And lets face it-the guy found the only clue in the whole ripper case, so lets give credit, where credit is due.

And re your balance of probabilites if the ripper would risk going out again_cmon Jeff, he just went from killing a woman, to minutes later, killing and mutilating another. The ripper was nothing, if not an extreme risk taker. Going back out to scribble some graffiti and drop the apron would have been peanuts to him. Peanuts.
Besides, the events of the night show that he even has a motive for doing so-getting back at those pesky jews for interupting him, and it also explains the missing time (and WHY it wasnt there the first time for Long to see it)because he had to go back to his bolt hole, and among other things grab some chalk.

On this one my friend, Im afraid you are quite wrong.

Hi Abby,

I have never said that I thought PC Long was lying, so there was no need to include that. And you may believe I'm wrong, but that doesn't mean I am. And your conviction appears to be quite strong on that belief, but that conviction in no way changes the fact that I am correct when I say it is possible PC Long was mistaken. The idea that he cannot be mistaken defies reality - people can be mistaken about many things.

Now, I may have overestimated the probability he's mistaken, but I've admitted to that and made it clear that I'm aware of that. But thinking that it is impossible that PC Long could truly belief the apron wasn't there despite it actually being there (i.e. he's mistaken) is, in your words, quite wrong.

It's fine if you think I've just grossly overestimated the likelihood of him being mistaken, I have no way of objectively determining the probability he missed it, in part because there's too little information on exactly what he did when he passed at 2:20? Where in the street was he? Was he on the far side of the street or the same side, for example? Was he just walking by and looking up into the stairwells for rough sleepers or was he checking the landing area, ground? Was he using his lamp at the time? and so forth. We have no information about his movements, positions, or actions, as he passed that area, so how can we be so sure he couldn't have simply failed to notice it? I can't be, so I have to consider both possibilities. And given he either saw it or he didn't, that means I have to weigh each option as they are mutually exclusive, which is where the probabilities come into it (they're just the "weight" one gives to each of those divergent options).

Anyway, we are disagreeing on those weights really, and as I say, I'm not claiming to know what the proper weighting is, only stating how I see them. I do think it is an error to weight the "overlooked it" option as 0 (impossible) given what information we have, and to go only with the "it wasn't there" option as if it is a known fact. If you don't think that, and agree there is some possibility that PC Long could have missed the apron, then we only disagree on how large that possibility is (and I've said many times, I don't know what the correct value is, but I think it's fair to say that in our subjective evaluations mine is higher than yours).

- Jeff

[JeffHamm]

this is incorrect, but expected.Not all areas of research utilize probability.

Probability is not useful directly in analyzing historical sources.

But I perfectly agree: we approach the topic with different perspectives and that leads to disagreement. I’m an historian and you’re a statistician or similar. Our methodologies differ. Personally, I believe I’m on safer grounds since this case is a historical one and must be approached as such, but You’ll probably disagree

No worries. The best collaborations are always with those who have different approaches to things. That's why I like these boards, there's many different ways to approach the information, and so I learn a lot.

- Jeff

[JeffHamm]

Gentleman, I realize this isn't the main thrust of what is under discussion, but let me throw it out there, because I have an opposing view.

Isn't the concept of the murderer 'reemerging' or 'venturing out again' influenced by the widely held--but quite possibly mistaken--belief that the murderer was a local man, with a remarkable ability to allude the police, and maybe even some 'daring'?

Why must it be so?

If Long was not wrong, and I have no reason to believe that he was, the inordinate delay between cutting the apron and depositing the apron might be explained by the murderer not having particularly good knowledge of local geography; as he made his getaway, he got 'turned around,' lost his bearings in the dark, and was thus literally wandering the streets for the better part of 40 minutes.

He never 'reemerged' because if never returned home to begin with.

In short, his supposed expertise of local geography is not in evidence. He was flat-out lost.

Hi rj,

I had briefly mentioned that option in one of my posts but had dismissed it as I believed that nobody believed JtR would hang around for that long carrying the apron piece. Clearly, I was mistaken! (what are the chances? )

To me, it seems if he was lost, and wondering in the area, he would have discarded the apron long before 2:20. I just can't see him carrying it around as it would be hard to conceal. Also, he's never very far from some of the major roads (Commercial, Whitechapel, etc), and so I can't see him being lost for that long. He would have to at least know the major roads. I've not seen this idea discussed before, though, so maybe there's more to it than I'm giving it credit.

Anyway, yes, the "re-emerge" version does seem to lock one into the "must have lived locally", and near that area. Interestingly, that would fit with the spatial analyses I've done (and yet, I still tend to think the "re-emerging" is the more improbable when compared to PC Long overlooking the apron).

- Jeff

[Herlock Sholmes]

Oh come on what is this coming to the killer wearing gloves now

www.trevormarriott.co.uk

Give me one half decent reason why the killer couldn’t have worn gloves? This was a killer who remained undetected after all. He wasn’t concerned about fingerprints of course but he wouldn’t have wanted to be seen with blood on his hands. Should we really assume that he couldn’t have considered gloves, or removing an overcoat before mutilating his victim for that matter? Killers often take precautions so why should we assume that the ripper was any different?

[Abby Normal]

Hi Abby,

I have never said that I thought PC Long was lying, so there was no need to include that. And you may believe I'm wrong, but that doesn't mean I am. And your conviction appears to be quite strong on that belief, but that conviction in no way changes the fact that I am correct when I say it is possible PC Long was mistaken. The idea that he cannot be mistaken defies reality - people can be mistaken about many things.

Now, I may have overestimated the probability he's mistaken, but I've admitted to that and made it clear that I'm aware of that. But thinking that it is impossible that PC Long could truly belief the apron wasn't there despite it actually being there (i.e. he's mistaken) is, in your words, quite wrong.

It's fine if you think I've just grossly overestimated the likelihood of him being mistaken, I have no way of objectively determining the probability he missed it, in part because there's too little information on exactly what he did when he passed at 2:20? Where in the street was he? Was he on the far side of the street or the same side, for example? Was he just walking by and looking up into the stairwells for rough sleepers or was he checking the landing area, ground? Was he using his lamp at the time? and so forth. We have no information about his movements, positions, or actions, as he passed that area, so how can we be so sure he couldn't have simply failed to notice it? I can't be, so I have to consider both possibilities. And given he either saw it or he didn't, that means I have to weigh each option as they are mutually exclusive, which is where the probabilities come into it (they're just the "weight" one gives to each of those divergent options).

Anyway, we are disagreeing on those weights really, and as I say, I'm not claiming to know what the proper weighting is, only stating how I see them. I do think it is an error to weight the "overlooked it" option as 0 (impossible) given what information we have, and to go only with the "it wasn't there" option as if it is a known fact. If you don't think that, and agree there is some possibility that PC Long could have missed the apron, then we only disagree on how large that possibility is (and I've said many times, I don't know what the correct value is, but I think it's fair to say that in our subjective evaluations mine is higher than yours).

- Jeff

Hi Jeff
Of course he could have missed it. But there is no evidence he did- I just think we get on slippery ground when we start discounting witness statements when there is no reason too. And again, this is the guy who found the only clue in the whole case, and yet you are going to not only not give him the benefit of the doubt (or the certainty, in his case), you are questioning his credibility. how does that work? It dosnt. So we can agree to disagree, but Im sorry Jeff you are quite wrong on this one.
But like kattrup, my background is in history, so perhaps that has something to do with how we approach the case.

[Scott Nelson]

Probability is not useful directly in analyzing historical sources.

This dilemma has always interested me. If historical sources cannot answer a question based on what's recorded, is it erroneous to undertake strictly a situational analysis, or can supplementing numerical modeling help? Not being an historian, I only have experience with the latter.

[JeffHamm]

Hi Jeff
Of course he could have missed it. But there is no evidence he did- I just think we get on slippery ground when we start discounting witness statements when there is no reason too. And again, this is the guy who found the only clue in the whole case, and yet you are going to not only not give him the benefit of the doubt (or the certainty, in his case), you are questioning his credibility. how does that work? It dosnt. So we can agree to disagree, but Im sorry Jeff you are quite wrong on this one.
But like kattrup, my background is in history, so perhaps that has something to do with how we approach the case.

Hi Abby,

Ok, so you agree he could have missed it, and that is really all I'm saying. He could have, and therefore we have to consider that possibility and where that would lead us. It's not questioning his "credibility", it is simply evaluating his statement. Given we have no record of his actions at 2:20 other than he was in the vicinity, we have no basis upon which to determine if his statement must reflect the reality of the apron. We can only evaluate whether or not he believed it was not there, and we both agree that is what he believes (I'm not in any way accusing him of lying, or covering up, or anything - I think he is genuinely stating that he did not see the apron when he passed at 2:20).

Let's look at the inquest testimony (From the Times, as recorded in the official documents section of Casebook).

[Coroner] Had you been past that spot previously to your discovering the apron? - I passed about twenty minutes past two o'clock.
[Coroner] Are you able to say whether the apron was there then? - It was not.
Mr. Crawford: As to the writing on the wall, have you not put a "not" in the wrong place? Were not the words, "The Jews are not the men that will be blamed for nothing"? - I believe the words were as I have stated.
[Coroner] Was not the word "Jews" spelt "Juwes?" - It may have been.
[Coroner] Yet you did not tell us that in the first place. Did you make an entry of the words at the time? - Yes, in my pocket-book. Is it possible that you have put the "not" in the wrong place? - It is possible, but I do not think that I have.
[Coroner] Which did you notice first - the piece of apron or the writing on the wall? - The piece of apron, one corner of which was wet with blood.
[Coroner] How came you to observe the writing on the wall? - I saw it while trying to discover whether there were any marks of blood about.
[Coroner] Did the writing appear to have been recently done? - I could not form an opinion.

There are a few things to note. First, despite being there and writing things down, he appears to have mis-recorded the spelling of Juwes as Jews. Moreover, he could not form an opinion about how recent the writing was. That tells us that he must not have looked into the area all that carefully, otherwise he would know it was or was not there. For example, if he said "I noted the chalk writing at 2:20 but there was no apron under it, but I cannot form an opinion if it was written recently" then I would not consider the idea of him missing the apron as credible. It would also all but negate JtR being the author (barring people suggesting JtR wrote the graffiti, then came back to "sign" it with the apron later). On the other hand, if he had checked the area carefully he would have been able to say "The writing was not there either", in which case I would not be entertaining the idea that he missed it. I do try and avoid the "lie" card at all costs, but people can be mistaken quite easily).

But he does neither of those, rather he is unable to form an opinion about the age of the writing, that means he does not know if it was or was not there at 2:20. As such, there is evidence that points to him not checking the stairwell as completely as he would have had to for us to be sure he wasn't mistaken. He also appears to be mistaken in his observations for things he was there and recording (i.e. the exact text on the wall), so that makes me think it wise to consider that his recollection of what he saw at 2:20 might also be a bit less than robust.

With all that in mind, and I want to make this clear, I'm not claiming he must be mistaken, I'm only saying what you are, that "of course he could have missed it".

I just think that the implications that follow if he's correct leads to a more unlikely, and unnecessarily complicated, explanation for how the apron ends up in that location compared to the explanation that follows if he's mistaken. And because one option (mistaken) leads to explanations that in my opinion seem more likely to have occurred, I prefer the explanations that include PC Long being mistaken.

I didn't say, nor am I saying, that I reject all other explanations. Rather, I order them in terms of which seem more probable to have been the case. That ordering, and evaluation of what seems more likely, is, as I have said many times, subjective, so it's no big deal you order them differently. But that doesn't make either me or you "wrong", it just means we weigh things differently, and there's nothing wrong in that because unless there is some way to objectively calculate such things, there is no "wrong" or "right" to it; it's an opinion.

All research requires the evaluation of evidence, and drawing inferences, and different people will draw different inferences because they believe the evidence points to different things. Evidence often has multiple possible explanations, therefore the inferences we draw are based upon which of those explanations we decide makes the most sense (which is just another way of saying which explanation we think is most probable). If that weren't the case, research would just be a deterministic system, where everyone always agrees because there is only one path of inference to follow. These boards are a prime example of how that is not the case

Oddly, the "re-emerging JtR" theory is one I could spin as showing how it fits well with the spatial analysis I've done, but I know enough about spatial analysis of crimes to know that the high interest zone need not be narrowing in on a residence. I don't go that way because I also think the JtR locations (and therefore the "geographical profiles") may be influenced a great deal about the common spatial behaviours of the victims themselves, and so the locations do not entirely reflect JtR's decision making (this is the sort of thing a lot of people who do spatial analysis, and sell very expensive software, tend not to mention when talking to the press; anything that points to limitations might impact sales after all). Anyway, it could be that my tendency not to over-evaluate those "profiles" plays a part in how I evaluate the subsequent "JtR fleeing vs JtR re-emergent" vs "JtR lost"), and I'm just being very cautious as a result. As I say, the evaluation is subjective, and our decision making about such things is influenced by many factors, not all of them logical.

- Jeff

[JeffHamm]

This dilemma has always interested me. If historical sources cannot answer a question based on what's recorded, is it erroneous to undertake strictly a situational analysis, or can supplementing numerical modeling help? Not being an historian, I only have experience with the latter.

Hi Scott,

I should probably clarify, when I'm talking "probabilities" here they are not objective probabilities derived from some sort of statistical analysis. For example, let's say we had a database of all serial killers, we might work out how common is it for them to make it home, and then come back out within the hour to discard some evidence. Aethelwulf mentioned the example of Ted Bundy, which is one example. I'm sure there could be more, but low probability events do happen sometimes, so the fact there are some examples is not the same as showing there is a high likelihood of that behaviour occurring in the JtR cases.

The fact that it can occur is just saying something doesn't defy the laws of physics, it is possible. The fact that there are only a few examples of something, mean it is possible, but improbable. And the the fact that there are many examples of something mean it is possible and probable.

Objective probabilities for complex behaviours can be very difficult to work out because no two situations are exactly the same, so there will always be debate about what to count. For example, is Ted Bundy's returning to the scene many hours later without any evidence on him and acting on the opportunity to remove evidence from the scene really the same as what is being proposed, that JtR, within the hour, was out and about carrying incriminating evidence that he had already "made safe" by getting it home so he could leave it somewhere else? Do we count that as an example, or is it a "counter-example", where it shows that it is more probable they will not come out within the hour? I'm not intending on opening a discussion on the above, I'm only trying to describe why these kinds of things are so difficult to get objective values for.

But in the end, the inferences we make based upon evidence requires us to evaluate the reliability of the evidence (historians will, for example, evaluate the text of documents knowing "some of it will be propaganda from the day" and they try to see through that; they don't just accept things as written. And it is that "seeing through" that involves a subjective idea of probabilities, or likelihoods - "this statement seems likely to be just propaganda" or "is influenced by a desire to denigrate ..." etc). That evaluation will often be based upon looking at other sources of information, other evidence, and trying to work out an overall explanation that makes the most sense - which is just another way of saying has the highest subjective probability.

- Jeff

[JeffHamm]

Hi Abby,

I think it's the way I phrase things that leads to some of our disagreement. For example, in my post above I say "And because one option (mistaken) leads to explanations that in my opinion seem more likely to have occurred, I prefer the explanations that include PC Long being mistaken."

When I say "likely" there, that's simply a summarizing of the idea that the explanation seems simpler and requires fewer assumptions and so forth, and those characteristics of a theory give it more "weight" than a theory that requires a complicated set of explanations (Occem's razor). In my work it is common to phrase such things as likely (the simpler theory is the more likely one; or the preferred one, etc). To me, the idea that JtR drops the apron as he leaves the scene is a very simple explanation, while the idea that he goes home and comes back out is a much more complicated explanation just to get to the same point (Apron in Goulston Street).

And yes, PC Long's statement does point against the simpler explanation, but PC Long's statement, like any witness statement, must in turn be evaluated. I've already gone through how that evaluation, in my view, lacks the necessary details about his actions for us to consider it as definitely indicating the apron was not there. Moreover, I've mentioned some things that I think are important to consider that suggest he may have overlooked it. In addition, we must always keep in mind that his statement is based upon his recollection of what he saw/did not see, and the influence of finding and taking note of the apron at 2:55, which in turn turns out to be an important clue, is exactly the kind of situation that can have very detrimental impacts upon the accuracy of our recollections (tonnes of research on memory tell us this). I'm currently running an experiment on our memory for thing (words in this case) that we actively are trying to remember vs those we note but decide are of no importance so we can ignore them. A bit removed in the specifics from a PC on patrol and so forth, but the general principle is what is important here. And what the earliest data is showing is that our confidence for things we ignored are reduced, both in terms of when shown an ignored word (confidence we did see it before is reduced) and when shown a new word from the ignored set (not as sure it is new, while new words from the actively remembered set are more confidently rejected). Meaning, even if he spotted the apron, but dismissed it as an irrelevant piece of rubbish at the time, he is far more likely to forget he spotted it (there was no reason to remember a piece of rubbish after all). Put on top of that the highly important event of finding it at 2:55, that is going to create a strong memory for it's discovery and it will tend to result in that previous incidental memory getting further reduced.

Memory is not very reliable, which is a bit disturbing really, particularly for things that we only incidentally experience. As a result, without further information on PC Long's specific actions, I'm left with having to factor in things we know about the reliability of memory along with the possibility that he simply failed to even see the apron at 2:20 despite it being there.

I'm not saying "he forgot it", though, I'm just saying that is yet another possible explanation that we have to include. The information we have about the JtR crimes is minimal and as a result there are many many things that could have happened. I'm just saying that we have something like this:

.................................................. Apron........................
.......................................there ............not there
PC Long: did not see it........ N..................... Y -> he believes it was not there, as he testified; explanation -> it wasn't there to be seen
PC Long: did not see it........ Y...................... N -> he believes it was not there, as he testified; explanation -> he missed it
PC Long: did see it..............Y..................... N -> he believes it was not there, as he testified; explanation -> he forgot about it (it was an unmemorable piece of .................................................. .................................................. .................................................. ......rubbish at the time he saw it )
PC Long: did see it............. Y .....................N -> he believes it was not there, as he testified; explanation -> his discovery of something important modifies his .................................................. .................................................. .................................................. ......memory of having spotted that something which was
.................................................. .................................................. .................................................. ......deemed unimportant earlier)

PC Long: did see it ............ Y ..................... N -> he testifies it was not there ; explanation he's lying because he would look bad (I discount this as improbable because if it were the case I believe he also say the writing was not there with equal confidence)

Hopefully that "table" doesn't get messed up when I post this.

Anyway, from what we know, any of those are possible ways to produce the evidence we have. I discount the last one "the he lied version" because I think that unlikely to begin with, but also because I think if he lied he would also have been just as prone to lie about the writing, and so would have been prone to say the writing was not there too. He doesn't, and his responses indicate he cannot be sure if the writing was or was not there at 2:20. As such, I think the "lie" explanation can be discounted.

But that still leaves us with a few ways that can lead to him believing the apron was not there despite the apron actually being there. And we cannot dismiss any of those because we do not have enough information to do so. We cannot, and should not, evaluate evidence based upon it's an important clue so let's give the guy the benefit of the doubt. In my view, because it is an important clue we should be very careful not to just give him the benefit of the doubt, but rigorously examine all the possibilities to make sure we utilize this clue properly.

I think it is very easy to overlook something, particularly a piece of rubbish (which is what it would have been to PC Long at 2:20, just another piece of rubbish), so I think the "he missed it" explanation has a fair deal of weight to it. As an anecdotal example, on two recent occasions my partner couldn't find her wallet, and on one of them she was worried she had lost it or left it somewhere. In both cases she had searched all over the apartment. In the first case, I spotted it on the table, where she had looked shortly before and even where she often leaves it. She just missed it. On the second, she had searched both the apartment and the car. I started looking around the apartment, couldn't find it either, and went to check the car as well. Sure enough, it had fallen under the driver's seat, and was a bit obscured from view, which is why she missed it when she looked (I used a flashlight, which she didn't, hence I looked the hero again! ). Anyway, I'm sure we all can think of such situations, and these are from active searching for the very thing overlooked. Sure, it's far more likely one spots it, but then, one is looking for it. What's important is how common it is to miss things even when we are looking for them specifically. Shift to a situation like PC Long, where he's not actively looking for pieces of cloth, etc, and overlooking becomes more and more probable.

I also know enough about human memory that it is also entirely possible that he simply forgot seeing a piece of rubbish earlier could happen, or even that the importance of the discovery at 2:55 could modify his recollections of what he saw at 2:20 (that is far more common than we like to believe).

What I would want to do, if it were possible, would be to get more details about exactly what PC Long did at 2:20. What was going on during his patrol? It was the first time he patrolled that beat that night, and he didn't even realize there was a back entrance to the buildings. His lack of familiarity with the beat would mean he may in part have been concentrating on learning the area when nothing untoward is happening (and seeing a piece of rubbish is hardly going to be considered "untoward").

There are too many ways open to us that allow for him to believe the apron was not there at 2:20 when in reality it was that I do not think it is wise to shut the door on them and give him the benefit of the doubt. But I'm very cautious about shutting doors, and I tend to try and arrange things in terms of which theories I think are more or less "weighty" (or probable, or whatever term one wants to use).

It's similar to how I don't discount Eddowes and JtR entering Mitre Square from Mitre Street or even the Duke's passage entrance. I can't be sure that the Church Passage Couple is definitely JtR and Eddowes. I do, however, think that is the most supported theory we have, and so it is what I would call the "most probable" theory, but I don't reject entirely the others. I just think they are less preferred given what we know.

That's all I'm saying, that in my view the "JtR drops it as he flees" is the theory I put at the top of the list in terms of theories that are still in the running, so I call that the "most probable" theory.

- Jeff