According to a new police report, obtained by TMZ, officers in Vegas responded to a call for service reporting an unresponsive person on Friday ... which turned out to be Adam. The responding officers arrived and confirmed he was deceased, and then were told more of the backstory of what apparently happened in the days leading up to this tragedy.

As it turns out, cops were told Adam had been staying in a guest house at this property -- and noted he had just been released from jail after serving 3 months behind bars ... although it's unclear what exactly for. The landlord said he needed a place to stay upon release, and they offered this guest house as somewhat of a kindness.

Officers interviewed a handful of roommates who had been living there as well ... and they said they hadn't seen Adam come by the main house in a few days. When they tried checking on him via social media, the roommates said they got a message back from him saying he was ill and quarantining.

However, when he continued to be off the radar thereafter ... the roommates told police that they tried knocking on his door, but said he never answered. At that point, they got the landlord involved -- who opened up Adam's unit ... only to find him lying unresponsive on his bed.

The roommates told officers that while his stay there at the property had been brief -- just two weeks or so, it seems -- they relayed behavior of his that they perceived as erratic and strange ... including allegedly barricading himself inside his little guest house there.

The roommates also claimed to cops that they suspected Adam had had a history of drug use too. As we reported ... Adam died of a fentanyl overdose, confirmed by his family.

Rick himself tells TMZ ... "Fentanyl turned my son into someone he wasn’t and that brought with it bad decisions and spending time in jail." Adam was only 39.