Philadelphia, PA (Sports Network) - Garrett Reid, the son of Philadelphia Eagles head coach Andy Reid, died in August of an accidental heroin overdose, according to a report from a Philadelphia television station.

The Northampton County District Attorney is expected to release details of its investigation during a news conference Thursday afternoon, but WPVI-TV in Philadelphia cited sources as saying the cause of death was heroin.

Garrett Reid died Aug. 5 at the age of 29. He was found dead in a dorm room at Lehigh University, site of the Eagles' training camp.

The younger Reid had battled substance abuse for a few years, spending time in jail as a result, and Andy Reid had mentioned the drug problems in the immediate aftermath of Garrett's death.

10/18 13:08:32 ET