Football concussions have now been fingered as a possible cause for the shooter suspected of killing four and injuring nine at Old National Bank in downtown Louisville, Kentucky.

As Awr Hawkins of Breitbart News reported on Monday, the suspect was identified as Old National Bank employee Connor Sturgeon, “a 23-year-old portfolio banker who listed his pronouns on LinkedIn as ‘he/him.'”

Connor Sturgeon/LinkedIn

“Four innocents were killed in the attack and another eight individuals were wounded. Two police officers were among the wounded,” Hawkins reported. “The attacker was deceased after police engaged him. As of late Monday morning, the Louisville Metropolitan Police Department (LMPD) did not know whether Sturgeon died via a self-inflicted wound or by being shot by police.”

After several outlets began digging into Sturgeon’s past, media figures and outlets instantly seized upon the fact he had endured multiple concussions while playing football to the point he needed to wear a helmet playing other sports like basketball.

“We played football together in eighth grade. He was out most of the year because he had multiple concussions,” one classmate told The Daily Beast. “Then he had a couple more in high school.”

“We played football together in eighth grade. He was out most of the year because he had multiple concussions,” he said. “Then he had a couple more in high school.”

Facebook/Lisa Sturgeon

The classmate linked Sturgeon’s injuries to other cases of athletes who exhibit aggressive behavior after concussions. Per the New York Post:

In recent years doctors have made numerous links between football players and Chronic Traumatic Encephalopathy [CTE], a degenerative brain disease caused by repeeated blows to the head.

Those diagnosed with CTE usually have impaired thinking and memory and are prone to aggression, mood swings, depression and paranoia, according to the Concussion Legacy Foundation.

Disgraced New England Patriots tight end Aaron Hernandez, who was convicted of murder in 2015, was found to have had chronic CTE after his 2017 prison suicide.

Various media figures have speculated if the concussions contributed to Sturgeon’s behavior and wondered if the time has come to regulate football.

As Breitbart News reported in February, Democrats in the state of New York introduced a bill to ban children from playing tackle football, arguing that it puts them at undue risk of injury. Dubbed the John Mackey Youth Football Protection Act in honor of former NFL player John Mackey, a New York native who died of traumatic encephalopathy (CTE) in 2011, the bill aims to ban all tackle football for children 12 and under.

Assemblyman Michael Benedetto, a Democrat representing the Bronx, has been pushing the bill for ten years and now has a sponsor in the New York State Senate: Democrat Luis Sepulveda.

“While the Super Bowl is an awful lot of fun, it’s not fun when you see young children run around, playing a game that they are hitting their heads, dozens to a hundred times a week – brains that are rapidly developing,” said Benedetto. “Ninety percent of brain development happens up until the age of 12 years old, give or take a year. During this particular time, why are we putting children at risk for injury to their brains?”