Junior Seau had no alcohol or illegal drugs in his system when he shot himself in the chest at his home in May, authorities said Monday.
The San Diego County medical examiner's office released the full autopsy results for the 43-year-old former NFL linebacker, saying he used an unregistered .357-caliber revolver to kill himself.
"No alcohol, common drugs of abuse or medication were detected," read the report, which was filed by deputy medical examiner Craig Nelson. "Based on the autopsy findings and the circumstances surrounding the death as currently understood, the cause of death is perforating gunshot of chest and the manner of death is suicide."
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.
The Associated Press contributed to this report.