The family of Aldon Smith has decided to send his brain to medical experts in Boston to see whether chronic traumatic encephalopathy (CTE) played a role in the former NFL defensive lineman's death.
Smith died Saturday at the age of 36, hours after he had delivered pizzas to a homeless charity.
No cause of death has been given. Smith's family has hired attorneys to help investigate his death.
"As with anyone who dies so suddenly at such a young age, we understand that there is a great deal of interest in and speculation about Aldon Smith's passing and we intend to get to the bottom of it," attorneys Harry Daniels, Bakari Sellers and Wayne Kendall said Tuesday in a statement. "To that end, we have taken a number of steps including sending his brain to Boston where medical experts will examine it for CTE as well as other damage caused by years of concussions and additional trauma.
"In the meantime, we simply ask you to keep Aldon's family in our prayers and respect their privacy as they struggle to come to grips with this terrible loss."
CTE is a degenerative brain disease that has been found in athletes in contact sports, combat veterans and others exposed to repetitive head trauma. It has been known to cause violent mood swings, impulsive behavior and depression. It can only be diagnosed after death.
According to the family, Smith suffered numerous concussions during his NFL career.
As a rookie, Smith burst on the scene with 14 sacks and 27 quarterback hits on his way to finishing second in Defensive Rookie of the Year balloting. He followed with his best NFL season in 2012, posting 19.5 sacks and 29 quarterback hits as he earned Pro Bowl and All-Pro honors. Those 19.5 sacks still stand as a 49ers franchise record for a season.
Smith's rapid ascent to NFL stardom was slowed by a series of off-field issues that included 10 arrests in nine years. That included an arrest on suspicion of driving under the influence in Miami in 2012, another on the same charge in San Jose in 2013 in which he crashed his car into a tree, and an arrest for three felony charges of possessing illegal assault weapons in October 2013.
The NFL suspended Smith for nine games in 2014 for violation of the league's personal conduct and substance abuse policies. On Aug. 7, 2015, the 49ers released Smith after a third DUI-related arrest. His release came the day after he was arrested on hit-and-run, DUI and vandalism charges.
Smith signed with the Raiders in September 2015, but the NFL suspended him for a year in November 2015 for again violating the league's substance abuse policy.
Amid suspensions that kept him out of football from 2016 to 2019, Smith appeared in nine games for the Raiders in 2015 and was conditionally reinstated by the NFL in May 2020. He appeared in 16 contests for the Cowboys in 2020. He had 3.5 sacks for the Raiders and five for the Cowboys, with his last one coming against the Philadelphia Eagles on Nov. 1, 2020.
Smith attempted one more comeback with the Seahawks in 2021 but was arrested on a second-degree battery charge in Louisiana soon after signing with Seattle. The Seahawks waived Smith on Aug. 11, 2021, for what a source described to ESPN's Brady Henderson as an "off-the-field matter."
In 2024, Smith began an initiative to help young athletes adjust to the pressures and pitfalls of such a high-profile job. He launched a project called "I.M. Loading," whose goal was to offer mentorship and recovery coaching for those who had endured similar life challenges.
ESPN's Nick Wagoner contributed to this report.