What led to troubled ex-NFL star Lawrence Phillips’s suicide?

Lawrence Phillips made his name in the blaze of stadium lights and roaring crowds – but he died alone, in a prison cell, leaving a troubling question: why?

Guards at California’s Kern Valley state prison found the former NFL running back unresponsive in his cell shortly after midnight on Wednesday, soon after which he was pronounced dead at a hospital.

The California department of corrections and rehabilitation is investigating the death as a suicide.

If confirmed, that would resolve the cause of death but not the reason why a life so full of promise unravelled into violence and desolation.

Was the 40-year-old an incorrigible thug destined for self-destruction? Did football damage him? Did prison break him?

Phillips, one former NFL player said, was a troubled character “from the get-go”. But some in the game believe a brain autopsy would reveal chronic traumatic encephalopathy (CTE), a disease linked to concussion and sub-concussive blows suffered in training and games. Others suggest he was unhinged by the isolation of a segregation unit – “a pretty serious formula for losing your mind”.

The most obvious explanation for suicide is that on Tuesday, hours before he was found in his cell, Phillips learned at a preliminary hearing that he could face the death penalty for murder. A superior court judge ruled that there was "sufficient cause to believe" the former St Louis Ram murdered a cellmate, Damion Soward, in April 2015.

Phillips had been in prison since 2008, serving a 31-year sentence for twice choking his girlfriend in 2005 and for driving a car into three teenagers after a pickup football game in Los Angeles.

Jesse Whitten, Phillips's attorney, told USA Today his client had expected to win any murder trial. "There was nothing about his demeanour that made me think he was suicidal at all, or depressed," Whitten said. "He was very confident about winning this case and he was even optimistic about his appeal on his prior cases."

However, letters from Phillips over the past year depicted a grim existence behind bars – anger, ennui, alienation and an ever-present threat of violence.

He had a rough start in life, growing up in foster homes in California, but sublime athletic talent offered a way out.

He became the star running back on the University of Nebraska's national championship teams in 1994 and 1995 and later played three seasons with the St Louis Rams, Miami Dolphins and San Francisco 49ers. Former Rams coach Dick Vermeil called Phillips the best running back he had ever coached.

His career foundered, however, for bad behavior on the field and brutal violence off it, running up a lengthy rap sheet for violence against women and, in 2005, running over the teenagers, landing him in Kern valley.

“Of all the cases of wasted talent in football – and there are many – Phillips may have had the most talent to waste,” Deadspin concluded in 2009.

In letters in 2014 to Tony Zane and Ty Pagone, former high school coaches, Phillips described grim regular stabbings between gang members and lockdowns but sounded reflective and resilient:

“All they want to do is the drugs, make knives and make alcohol. Then they say when they get out they will not come back. I tell them of course you will. You are doing the same things that got you locked up. Of they course they do not want to hear that. It is like speaking to a brick wall.”

In a separate letter: “It is completely nuts in here. It is pretty much a free for all.”

Phillips sounded very bleak in a March 2015 letter to his mother: “I feel myself very close to snapping. My anger grows daily as I have become fed up with prison. I feel my anger is near bursting and that will result in my death or the death of someone else.”

A few weeks later guards found his cellmate, Soward, dead from apparent choking. Phillips was subsequently held in the prison’s administrative segregation unit, which is known for imposing extreme isolation.

His death on Wednesday left some former NFL players speculating about brain damage from the game.

"I'm not blaming everything on CTE but when you get hit in the head you don't think like other people," said Dave Pear, 62, a former Super Bowl champion with the Oakland Raiders who suffered brain damage. "His bursts of anger, the mood swings – those are all things that I go to doctors for."

Pear, who runs an influential players’ blog, said he hoped Bennet Omalu would get to look at Phillips’s brain. “I’m certain he’ll find CTE in there.”

Omalu is the forensic pathologist who discovered CTE, which has ravaged former players such as the Pittsburgh Steeler “Iron Mike” Webster, a story told in the film Concussion, starring Will Smith.

George Visger, 56, a former defensive lineman for the San Francisco 49ers who also has brain damage, said he did not want to make excuses for Phillips's behaviour. "I hate to pin it on brain damage. He seems to have been a criminal from the get-go. But it might have been a contributory factor."

Dustin Fink, an Illinois athletic trainer who blogs about brain injuries, agreed CTE was possible but said short of an autopsy there was no evidence. Another potential factor, he said, was that pro football drew "certain dispositions, that of a gladiator, an aggressor".

Penal reform activists pointed to another factor – months of isolation in administrative segregation. According to the UN Special Rapporteur on Torture, solitary confinement exceeding 15 days constitutes torture.

"Ad seg is the worst form, the most isolating," said Laura Magnani of the American Friends Service Committee, a Quaker advocacy group. "You are really very, very isolated. You have very little contact with other humans." Extended isolation, she said, was "a pretty serious formula for losing your mind".

Geri Silva, an activist with Families to Amend California's Three Strikes, said such isolation would affect anyone's mental health. "You're surrounded by nothing – just four walls."

Last September California agreed to end the unlimited isolation of gang leaders, restricting a practice that once kept hundreds of inmates in segregation units for a decade or longer. No other state uses the practice as extensively, according to the Center for Constitutional Rights.

(Guardian service)