The suspect involved in a fatal weekend shooting in Massachusetts that left two innocent bystanders dead was in possession of handwritten notes containing white supremacist rhetoric. The shooting is now being investigated as a hate crime.

The gunman, 28-year-old Nathan Allen, stole a box truck on the afternoon of June 26, and rammed it into a home although no one was inside at the time. Allen then got out of the vehicle and shot two Black bystanders, 68-year-old David Green, a retired Massachusetts State Police trooper, and Ramona Cooper, a 60-year-old Air Force veteran.

“There’s some troubling white supremacist rhetoric that was found,” in Allen’s handwriting, said Suffolk District Attorney Rachael Rollins, according to Boston 25 News.

When Winthrop police arrived at the scene of the crash, they found one shooting victim about a half a block away. According to Winthrop Police Chief Terence Delehanty, Green, the other victim, is thought to have “engaged with the suspect” in an alley near the crash and was shot.

Cooper was shot three times in the back and was pronounced dead at the hospital while Green was shot four times in the head and three times in the torso and died at the scene. Green served in law enforcement for 36 years and was killed outside of his home.

“We at the Massachusetts State Police are also mourning the loss of a member of our family,” state police said.

Allen was fatally shot as officers tried to apprehend him. Delehanty praised the unidentified sergeant who shot Allen, saying he “isolated a significant threat to this community and ended that threat.” Allen was armed with two weapons and one officer sustained a non-life threating gunshot wound during the ordeal.

In a statement, Rollins elaborated on rhetoric written by Allen. “This individual wrote about the superiority of the white race. About whites being ‘apex predators.’ He drew swastikas,” she said.

Rollins also said Allen was married, employed, had no criminal history and had a Ph.D. She added that he “was not on my radar,” and had a license to carry a firearm.

Rollins said it’s likely Allen targeted his victims because they were Black, saying that at the scene “he walked by several other people that were not Black and they are alive. They were not harmed.”

She explained that Allen “stole a box truck, crashed it into another vehicle and a property, walked away from the wreckage interacting with multiple individuals and choosing only to shoot and kill the two Black people he encountered.”

She also noted that Allen, who had written anti-Semitic rhetoric, crashed the vehicle in an area with Jewish synagogues.

Rollins didn’t provide further details about Allen’s notes or where they were found but said the investigation is still in its early stages.

“This is a sad day, Rollins said. “These two people protected our rights. They fought for us to be safe and to have the opinions that we have, and they were executed. We will find out why and find out more about this man that did this.”

According to witnesses, Green tried to stop Allen once he realized Allen was armed in order to protect those around him.