its an excellent point about the door not being damaged in the newspaper and one I would not have twigged .. very observant of you . I think a lot of assumptions are and were made about this case... did a police man break in or suzys dadThe simplest explanation is that he assumed there weren't any. The police on Monday assumed he'd been inside 37SR that day and did not themselves go there until the next day. They then got in, somehow. They were unable to get into SJL's own flat without breaking the door down, but they were able to get into 37SR without doing so. The press photos the next day showed an undamaged door.
So at some point on the Tuesday, it occurred to the police that it might be quite a good idea if someone had a look around 37SR, in case SJL was there. They entered using a key, the only one Sturgis had. Presumably they turned up at Sturgis the next day, asked if there was a key to 37SR and were given it.
If it had been troublesome to get in you'd expect someone - AS, the detectives interviewed - to remember. They remember having to break into SJL's flat but getting into 37SR presented no memorable problems at all.