How reliable were the alibis?

[Harry D]

There's quite a few minor suspects arrested during the Ripper investigation who aroused suspicion for one reason or another. That's where I personally think we'll find our guy, in those archives. Most of them were able to give an account of themselves on the nights in question. How reliable were these alibis? For example, the people who were sleeping in doss houses at the time. How easy would it have been for someone to sneak in and out as they please? Did the doss houses have watchmen making sure everyone was tucked up in bed? I find that hard to believe. How thoroughly would the police have checked into them?

[Wickerman]

In most cases the police would ask the name and address of the person detained, and their place of work.
The police would then go to that address, verify with someone at that address the name & description of the person who claimed to live there, and or likewise at their place of work, and that was the extent of their enquiry.
Basically the police want to verify that they are who they claim to be.
Unless of course there was something more suspicious involving the reason why they were detained in the first place.

The police were not stupid, checking the personal details of someone who was registered at a Doss house was no certainty they were telling the truth.
Everyone residing at a Doss house came from somewhere, they do work, or have worked somewhere, they know somebody or knew somebody of a reliable status in life, Doctor, Landlord, employer, relative, sibling, everybody knows somebody. So, somebody 'knows' him - the purpose is the same, to verify the person is who they claim to be. The fact they now live in a Doss house is irrelevant.

Depending on how much suspicion was attached to this person will decide how deep the police will investigate his background.