Former NFL star Junior Seau committed suicide by shooting himself in the chest, autopsy results confirmed, according to San Diego County authorities.
Seau, a hugely popular NFL veteran, was found wounded at his beachfront home north of San Diego on Wednesday by his girlfriend, who notified authorities.
Emergency crews were unable to revive him and he was pronounced dead at the scene.
Although he left no suicide note, the county medical examiner's office said Thursday that an autopsy confirmed suspicions that he had taken his own life.
The precise time of his death was unclear, county spokeswoman Sarah Gordon said.
Deputy Medical Examiner Craig Nelson performed the autopsy, including an examination of the body and organs and collection of "appropriate specimens for laboratory studies including toxicology and microscopic examination of organs and tissues," the medical examiner's office said in a statement.
Gordon added that the medical examiner will await the Seau family's decision on whether to examine Seau's brain for evidence of repetitive trauma possibly suffered during his NFL career.
Although friends and family said they had no indication Seau was depressed, speculation immediately arose as to whether Seau was battling depression that recent research has linked to multiple concussions suffered by NFL players and other sportsmen.
Sports Illustrated reported that researchers at Boston University, a leader in the study of brain injury, have asked to examine Seau's brain, although the university did not confirm the report.
Seau was not known to have suffered concussions during his playing career, but his ex-wife, Gina, told ESPN: "Of course he had. He always bounced back and kept on playing. He's a warrior. That didn't stop him. I don't know what football player hasn't. It's not ballet. It's part of the game."
In 2009, the NFL adopted stricter guidelines on treating concussions in the league after Congress held a hearing on the topic.
The issue was in the spotlight again last year when former Chicago Bears safety Dave Duerson, a two-time Super Bowl champion, fatally shot himself in the chest, leaving a suicide note asking that his brain be donated for scientific study.
A researcher at the Center for the Study of Traumatic Encephalopathy concluded Duerson, who was 50 when he died, had brain damage related to repeated head trauma.
The CSTE, which is a joint venture between Boston University Medical School and the Sports Legacy Institute, has a brain bank that has the brains of more than 70 athletes and military veterans, with gridiron players making up more than half of the athletes as of last year.