Authorities are investigating a Massachusetts shooting that left two Black people dead as a hate crime after investigators found "some troubling white supremacist rhetoric" in the gunman's handwriting, officials said Sunday.
Suffolk County District Attorney Rachael Rollins, who identified the suspected gunman as 28-year-old Nathan Allen, said during a press conference on Sunday that investigators found "antisemitic and racist statements against Black individuals."
Allen was killed by police officers on Saturday afternoon shortly after stealing a plumber's truck, crashing it into a house and shooting two Black bystanders multiple times in Winthrop, just outside Boston, according to Winthrop Police Chief Terence Delehanty.
The slain bystanders, who were both Black, were identified as David Green, 58, a retired Massachusetts State Police officer; and Ramona Cooper, 60, an Air Force veteran who still worked with the military, according to Rollins. Allen shot Green four times in the head and three in the torso, and Cooper three times in the back.
"He walked by several people that were not Black and they are alive. They were not harmed," she said. “They are alive and these two visible people of color are not."
In a statement on Sunday, Rollins said Allen wrote about white people being "apex predators" and drew Nazi swastikas.
She did not specify where the writing was found but added that authorities are still investigating a motive for the shooting.
"These families deserve answers, and we will find out what happened here," she said.
Before crashing into the house, Allen allegedly drove the stolen truck into another vehicle with two passengers, Delehanty said. The two people were taken to the hospital with injuries that were not life-threatening.
No one was inside the home at the time of the crash, he said.
Allen, who Rollins said was married, employed, had a Ph.D. and no criminal history, "likely appeared unassuming." Then on Saturday afternoon, she said, he committed multiple crimes and chose "only to shoot and kill the two Black people he encountered."
"This is a sad day," Rollins said Sunday. Cooper and Green "protected our rights. They fought for us to be safe, to have the opinions that we have — and they were executed."
This article was originally published on NBCNews.com.