I've taken the plunge here and voted "no". A bit audacious of me, because I can't really be the best judge and "undecided" should be the logical choice. But the case against McKenzie feels wrong. The fury that so trademarked the ripper seemed to be so much less intense here. I think she was more likely the victim of a copycat killer.
By "fury" I meant that the wounds that he inflicted were, relative to the wounds on the earlier canonicals, relatively light, as I understand it. Even the most serious wounds to the abdomen didn't even injure the muscular structure. This was not like the forceful, furied, deep ripping frenzy that was typical of the ripper. There may have been a reason for this, maybe it was the ripper and he was just shattered by this time. But it doesn't feel right to me and so I'm inclined to think this was a copycat.
If Alice was, then she must have caught Jack on one of his off nights. After what happened to Mary Kelly, to go back to a seven inch scratch and some superficial cuts on his victim's abdomen is a bit of a change in his M.O. There also seem to have been stabs at rather than a deep slash of the neck. Perhaps he just couldn't be bothered anymore!
I believe that she probably was a Ripper victim. The simple fact is that prior to 1888 this would surely have been regarded as an incredibly rare crime. In fact, outside of 1888 murder itself was a rare event in Whitechapel. The Annual Report of the Sanitary Conditions of Whitechapel listed no murders at all in the Whitechapel area in 1886 or 1887 and only one murder was recorded in 1889 and 1890.
I would further argue that, prior to 1888, this type of crime would have been virtually unprecedented. In fact, before 1888, and after the Coles Murder in 1891, how many recorded incidence are there of women being found in the streets of Whitechapel with their throats cut or abdomens mutilated? Off hand I can't think of any.
And then there's the fact that, in typical Ripper fashion, her throat was cut whilst she was on the ground, possibly a stratagem to avoid arterial spray.
Dr Bond also believed that she was a Ripper victim, pointing out the similar MO, i.e. "the throat skillfully and resolutely cut with subsequent mutilation, each mutilation indicating sexual thoughts and a desire to mutilate the abdomen and sexual organs."
The main argument against was that the mutilations were no where near as extensive as that inflicted on MJK. However, she was killed indoors, where JTR could work without the likelihood of interruption. There is also the distinct possibility that her killer was disturbed as her body was still warm at discovery.
And given the rarity of this type of crime what really are the alternatives. A copycat killer? Surely they mainly exist in crime fiction, I mean, where's the evidence of a copycat Zodiac? Yorkshire Ripper? Jack the Stripper? And why wait several months after the MJK murder? I suppose William Bury's murder of his wife comes closest to a possible copycat JTR crime, but that happened in Dundee. And who knows? Maybe William Bury was JTR! He certainly used to be my favorite suspect!
The Alice McKenzie murder is one of the aspects of this case that most intrigues me. Looking at various sources, I think her exclusion from the "canonical" list is mainly due to the long gap between her death and the Kelly murder, and because her wounds were substantially less gruesome than Kelly's, which breaks the narrative of a killer escalating in his fury until his 'mind breaks' in Millers Court.
In reality, we now know serial killers can sometimes go years without committing a murder, and that there is not always a neat escalation in violence. Some have even been known to adapt their MO (Sutcliffe, for example, started strangling rather than coshing later victims).
From what I understand, there is much in common in McKenzie's death and those of the "canonical" victims. For example:
Mary Ann Nichols:
Killed on the ground in the street by having throat cut
2 distinct cuts to the throat, from the left to right
Stabs to private parts
Incisions to abdomen (exposing the intestines)
Bruises to face
Alice McKenzie's wounds are very similar, though apparently less savage (the wounds to the abdomen much shallower, and without the distinctive placing of the intestines over the shoulder evident in the Chapman and Eddowes murders).
In the case of Nichols, Chapman, Eddowes and Kelly I also understand their throats were cut very deeply, with scratches on the spinal column, almost enough to sever the head. However Stride, like McKenzie, only had a shallower cut to the left side of the throat, only partly severing the left carotid artery. If (a big If, maybe) we accept that Stride is a "canonical" victim and the murderer was disturbed or scared off, could the same not apply to McKenzie?
Given that the doctors involved in post mortems disagreed about whether "canonical" victims were killed by the same man, and given the police were concerned enough by McKenzie's murder to immediately step up the patrols in Whitechapel, I'm intrigued to understand why there is a general tendency to exclude McKenzie from the sequence of murders, and to include Tabram (whose death from multiple stab wounds looks, superficially, very unlike the murderer's typical MO).