Results from the autopsy, which will include a routine examination of his brain, were expected to be released later in the day, San Diego County Medical Examiner's office spokeswoman Sarah Gordon said.
During his 20-year National Football League career, Seau, 43, was not widely known to have suffered from concussions. The autopsy being conducted is limited to looking for manner and cause of death, but an examination of the brain will be included as it is routine, Gordon said.
"If the family makes requests for outside research, we will participate, with family consent," she said. At this point, the family has not made any such request, she said.
Seau retired after the 2009 season with the New England Patriots after spending most of his career with the Chargers.
(Reporting by Joseph Schuman; Writing by Alex Dobuzinskis; Editing by Cynthia Johnston and Philip Barbara)