The suspect named in this past weekend’s mass shooting allegedly had a history of violent behavior. Last year, he underwent a mental health evaluation after making threats against his high school, per reports from The New York Times.

Police confirmed that last June, Payton S. Gendron was escorted from his high school for making threatening remarks. Shortly after, he was taken to a hospital for a mental health evaluation after he said that his post-graduation plans “involved a murder-suicide.”

“The state police responded,” said Buffalo Police Commissioner Joseph Gramaglia during a Sunday (May 15) press conference. “They investigated. They interviewed the subject. And they felt at the time it was appropriate to have that individual brought in for a mental health evaluation.”

Gendron was later released after he described his comments a joke. Gramaglia also reported that the evaluation lasted for roughly a day and a half. According to F.B.I Special Agent Steven Belongia, the 18-year-old suspect was “not on the radar” of federal authorities.

On Saturday (May 14), Gendron entered a Tops supermarket in east Buffalo where he shot a total of 13 people. The attack left 10 people dead and 11 of the victims were Black.

“The evidence that we have uncovered so far makes no mistake that this is an absolute racist hate crime, Gramaglia continued. “It will be prosecuted as a hate crime. This is someone who has hate in their heart, soul, and mind.”

According to authorities, Gendron drove more than 200 miles to specifically target the predominantly Black area within the city. He visited the grocery store the night before his attack which was live streamed via Twitch.

Twitch confirmed that the livestream was removed within two minutes of the attack.

Officials also uncovered a 180-page document filled with racist and anti-immigrant statements that was shared online by someone using the same name as Gendron.