Authorities have said that on April 7, Adams killed Rock Hill physician Robert Lesslie; his wife, Barbara; two of their grandchildren, 9-year-old Adah Lesslie and 5-year-old Noah Lesslie; and two HVAC technicians working at the Lesslie home, James Lewis and Robert Shook, both 38. Police later found Adams with a self-inflicted gunshot wound to the head.
Adams' family agreed shortly after his death to have his brain tested for chronic traumatic encephalopathy, or CTE, the degenerative disease linked to head trauma and concussions that has been shown to cause a range of symptoms, including violent mood swings and memory loss.
Neuropathologists at the Boston University CTE Center conducted the autopsy and evaluation of Adams' brain. They released their findings Tuesday upon the request of Adams' family.
"As we process these results, we are deeply saddened by the events that occurred on April 7 and we continue to pray for the families of the victims," the family of Phillip Adams said in a statement. "We are pleased to have a better understanding of the mental turmoil that Phillip was dealing with during the last moments of his life. We cannot say that we are surprised by these results, however it is shocking to hear how severe his condition was."
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CTE, which can only be diagnosed through an autopsy, has been found in former members of the military, football players, boxers and others who have been subjected to repeated head trauma. One recent study found signs of the debilitating disease in 110 of 111 NFL players whose brains were inspected.
Adams, 32, played in 78 NFL games for six teams over six seasons. He joined the San Francisco 49ers in 2010 as a seventh-round draft pick out of South Carolina State, and though he rarely started, he went on to play for New England, Seattle, Oakland and the New York Jets before finishing his career with the Atlanta Falcons in 2015.
As a rookie, Adams suffered a severe ankle injury and never played for the 49ers again. Later, with the Raiders, he had two concussions over three games in 2012. Because he didn't retire by 2014, he wouldn't have been eligible for testing as part of a broad settlement between the league and former players over long-lasting concussion-related injuries.
The Associated Press contributed to this report.