Presley Gerber Death

Presley Gerber should have been turned away from the sober living home where he died of a suspected overdose and, instead, sent directly to a detox center ... a move people in his world think would've saved his life.

Multiple sources familiar with the situation tell us ... when Presley arrived Saturday evening at the sober living home in Santa Monica -- apparently under the influence -- staffers should have refused to admit him, because the house is not a detox facility.

We're told Presley should have been mandated to complete a medical detox program to ensure no drugs were in his system before he was admitted to the home ... or some other outpatient facility setup for detox.