How realistic was it for JTR to disguise himself as a PC?

[Leanne]

A window in the passage?
There's never been any reference to such a detail.

Was anyone interested in such a detail?

One press sketch:

[Sam Flynn]

I wouldn't read that as specifically meaning from each tenants room. Any resident passing through the court could see or look into Kelly's window(s).
I take it to mean any resident within the court, meaning on foot.

Indeed, but I was thinking primarily of the residents of the front rooms and/or upper floors of Miller's Court, like Mrs Prater, who'd normally have had no reason to go into the court itself.

[Wickerman]

All that's saying is that the window could be seen by any of the inmates of Miller's Court... which isn't strictly true,...

I wouldn't read that as specifically meaning from each tenants room. Any resident passing through the court could see or look into Kelly's window(s).
I take it to mean any resident within the court, meaning on foot.

[Wickerman]

Above is a diagrame of Millers Court. I believe there was an open window to No 26 (Storage) in the covered passage viewable to any residents entering from Dorset Street. The large window at the front would have been the one that was boarded up.

A window in the passage?
There's never been any reference to such a detail.

[Leanne]

[Sam Flynn]

Then why did the police check for bloodstains?

They'd have to apprehend someone first. A casual passerby, even a passing police officer, would be unlikely to spot any bloodstains on a dark jacket or trousers, especially in poor light.

[Leanne]

Above is a diagrame of Millers Court. I believe there was an open window to No 26 (Storage) in the covered passage viewable to any residents entering from Dorset Street. The large window at the front would have been the one that was boarded up.

[Leanne]

Assuming any dark stains would have shown up against the drab, dark clothing that most men wore in those days; clothing which, for some of the poorest, wouldn't have been strangers to stains in any case.

Then why did the police check for bloodstains?

[Sam Flynn]

FROM THE ABOVE LINK:

'The room, however, is really the back parlour of 26, Dorset-street, the front shop being partitioned off, and used for the storage of barrows, &c.

This was formerly left open, and poor persons often took shelter there for the night; but when the Whitechapel murders caused so much alarm the police thought the spot offered a temptation to the murderer, and so the front was securely boarded up.

ALTHOUGH THE WINDOW WAS OPEN TO THE OBSERVATION OF ANY OF THE INMATES OF THE COURT, the door was some distance from any other, and afforded the utmost facility for an easy escape.”

All that's saying is that the window could be seen by any of the inmates of Miller's Court... which isn't strictly true, BTW, because Kelly's window would have been in a bit of a blind-spot of some of the residents. Besides, the link is to a modern narrative on a website, not a primary historical source, so I wouldn't set much store by what it says.

[Sam Flynn]

So he was likely a local man who worked in a position where he was likely to be able to explain away the odd dark stain on his clothing, and had somewhere to hide stuff.

Assuming any dark stains would have shown up against the drab, dark clothing that most men wore in those days; clothing which, for some of the poorest, wouldn't have been strangers to stains in any case.

[Leanne]

FROM THE ABOVE LINK:

'The room, however, is really the back parlour of 26, Dorset-street, the front shop being partitioned off, and used for the storage of barrows, &c.

This was formerly left open, and poor persons often took shelter there for the night; but when the Whitechapel murders caused so much alarm the police thought the spot offered a temptation to the murderer, and so the front was securely boarded up.

ALTHOUGH THE WINDOW WAS OPEN TO THE OBSERVATION OF ANY OF THE INMATES OF THE COURT, the door was some distance from any other, and afforded the utmost facility for an easy escape.”

[Leanne]

https://www.jack-the-ripper-tour.com/generalnews/the-murder-of-mary-kelly/

[Leanne]

So he was likely a local man who worked in a position where he was likely to be able to explain away the odd dark stain on his clothing, and had somewhere to hide stuff.

[Busy Beaver]

What did he wipe his knife on?

Quite possibly the clothing of his victims. He would have been very stupid to wipe a knife over himself and walk through the streets and turn up to his home or work covered in blood stains. Especially if he was not employed in area where a knife could have been used and he did not look as if he was the one who got attacked. At the height of the Ripper scare if a man looked at a woman the wrong way, or was seen acting strangely the Police would have been called and that person was pulled into the station.

[Leanne]

What did he wipe his knife on?