SAN DIEGO >> No alcohol or illegal drugs were found in Junior Seau’s system when he shot and killed himself at his home in May, authorities said today.

The full autopsy results were released by the San Diego County medical examiner’s office in a 16-page report for the former NFL linebacker who was found by his girlfriend with a single gunshot wound to his chest.

Seau did have Zolpidem, often found in the sleeping aid Ambien, and traces of the anti-inflammatory drug naproxen in his system when he died that were “consistent with therapeutic use,” wrote Deputy Medical Examiner Craig Nelson.

The autopsy showed no underlying hemorrhaging or contusions on Seau’s brain, which appeared to be normal. His family has donated some of his brain tissue for research amid questions about whether any damage from his 20-year football career played some factor in his suicide.

Questions remain about why Seau, 43, decided to kill himself on May 2 at his suburban Oceanside home. No suicide note was found, according to the autopsy report, and family and friends said Seau didn’t appear distraught or depressed.   

Investigators said the gun Seau used to kill himself was an unregistered .357-caliber revolver that had five hollow-point bullets inside. They also found his cellphone lying on his bed. The phone had its memory chip missing.