Presley Gerber Suffered Cardiac Arrest Before Death at Rehab

Presley Gerber suffered cardiac arrest before he died at a Santa Monica rehab facility ... with emergency dispatch recordings also pointing to an apparent overdose.

People reports dispatch recordings show a call went out at 9:35 AM Sunday for a cardiac arrest at the facility. A separate dispatch alerted first responders to an overdose at the same address.

As TMZ previously reported, Santa Monica police officers found Presley unresponsive and provided life-saving measures. He was pronounced dead just 10 minutes after the initial call, at 9:45 AM.

Police are investigating his death as a drug overdose, and no foul play is suspected.

TMZ broke the story ... the 27-year-old son of Cindy Crawford and Rande Gerber died Sunday at the luxury rehab, where sources say he had been living in a separate house on the grounds with several other people.

Sources with direct knowledge told TMZ ... Presley's family was informed his death appeared to be the result of an overdose.

The Los Angeles County Medical Examiner has since completed Presley's autopsy, but his official cause of death has been deferred. The M.E. has not officially linked his death to an overdose or any specific substance.

Months before his death, Presley opened up about undergoing an "Ibogaine Flood Dose" treatment, saying he was terrified beforehand but hoped it would help him find his way back to himself.