It is at this point that Bell tells Holmes he's nuts. See, even though Bell has heard "good things" about Holmes and Gregson apparently thought this was a sufficiently baffling case to call in the famed consulting detective, the police already assume they know exactly what happened. Watson pops up to show the missing armoire in a convenient picture, so there. And there's no elevator in this building. The scratches on the floor go to the hallway, and Holmes is now suspicious of the neighbor, who's obviously the guy who stole the armoire. Holmes kicks in the door across the hall on the grounds that he doesn't need a warrant, since he's not a cop. So isn't he breaking and entering? Anyway, Holmes points at the neighbor: "Thief. Now all you need is your killer."
Ah! There is a title sequence after all! It's a Rube Goldberg device featuring a crystal ball and a mouse and violin music.
After the opening, we're in the interrogation room. The neighbor is apparently still a suspect, because he's telling Bell that Casey (the dead guy) was already dead when he found him. The neighbor seems to think "the economy" is a good reason to steal an armoire from what's obviously going to be a heavily scrutinized crime scene. Bell is leaning on him. On the other side of the one-way glass, Holmes considers this "wrong wrong wrong wrong." Gregson doesn't buy Holmes's theory about a separate murderer, because who goes around believing Sherlock Holmes? Not cops, that's for sure. Holmes gets angry until Watson sends him out to get a bag of chips. The balance of power in this relationship is very different from most Holmes/Watson duos. Watson interrogates Gregson about his previous relationship with Holmes. We don't learn anything earthshaking: "He was a pain in the ass, but he was also very, very good." Watson continues to pry and learns that Holmes called Gregson from Heathrow airport in London two weeks earlier.
Out at the snack machine, Holmes is eating the chips that he was supposed to be getting for Watson. The charitable interpretation is that he knew Watson was getting him out of the way. The cruel way to look at it is that this Sherlock Holmes has so little short-term memory that he forgot who the chips were for in the twenty seconds it took him to walk to the machine.
Bell comes out to tell Gregson that the neighbor won't admit to murder and that he wants a lawyer. Is that rare? It seems like most of the time, even when you've caught the actual murderer, they're not going to admit it just because you asked them nicely. The neighbor does claim to have passed a woman on the stairs, but even though he can provide a detailed description, Bell doesn't care. Because obviously he's making it all up. I really question why they called Holmes in on this, since the police all seem to think that this is a simple, open-and-shut case. Also, Bell calls Holmes "Harry Potter" which doesn't work on any level. He and Holmes talk over each other and Gregson eventually decides he'll accept Holmes's request for a sketch artist.