MM fiction about undercover job

[Mercury1911]

The guy's brother (if i remember correctly) dies, and in onder to investigate, he goes undercover, moves in with a guy who might be working for the ppl who killed his brother (?), but it seems unlikely, because he actually starts to like the guy.
Please of anyone know let me know

[Kris]

Mercury, is the hero an undercover cop or private eye/investigator/detective?

Around what year did you read this book?

[Mercury1911]

@kris, I think he was a cop. And the guy he moves in with, allegedly works for Russia mafia (well, some kind of mafia really). And he can't believe that he is actually invilved in all that stuff. See, i haven't read this book. I read the blurb some time ago, and now i can't remeber the title(

[Lobstergirl, au gratin]

Mercury1911, are you still looking for this or did you find it?