The former linebacker was found dead in his Oceanside home Wednesday morning. An autopsy concluded he shot himself in the chest. Police did not find a suicide note.
A forensic autopsy was also conducted, which included an examination of the body and organs, as well as toxicology tests and microscopic examination of organs and tissues. The final results of those tests will be part of the medical examiner's final autopsy report.
Some have speculated that brain injuries from football may have played a role in his death, but there has been no medical confirmation of such damage.
Seau is one of at least three former NFL players to have committed suicide in the last 14 months. Dave Duerson shot himself in the chest in February 2011, and Ray Easterling killed himself in February.
The football great was drafted fifth overall by the San Diego Chargers during the 1990 NFL Draft and played for the Chargers until 2002. He went on to play for the Miami Dolphins from 2003 to 2005 and the New England Patriots from 2006 to 2009. Seau was also a standout player at University of Southern California.
The Associated Press contributed to this report.