Junior Seau had no alcohol or illegal drugs in his system when he shot himself in the chest at his home in May.
The San Diego County medical examiner's office on Monday released the full autopsy results for the 43-year-old former NFL linebacker, saying he used a .357-caliber unregistered revolver to kill himself.
The 16-page report said Seau did have Zolpidem, used to treat insomnia, and traces of Naproxen, a common drug used to relieve pain and stiffness caused by osteoarthritis, in his system when he died.
The autopsy said Seau's brain didn't appear to have any trauma. His family has donated some of his brain tissue for research.
Seau died May 2. The report said no suicide note was found.