controlled substance. they said they found the largest amount of drugs in robert's apartment. they learned his cell phone did have hoffman's number stored in it. >> one of the nicest people i have ever met. smart. he goes out of his way to be nice. knows everything about film and music and art and literature. great guy. >> investigators trying to determine if any of them sold drugs to hoffman. they could be looking at more serious charges. possible prosecution under the so-called felony murder rule when someone dies after the commission of a felony. it happened in the john belushi case to kathy smith and she served 15 months behind bars for injecting him with the fatal dose of heroin laced with cocaine. >> the felony murder rule, you attempt to apply it to a drug