WINTHROP, MASS. (WHDH) – Officials said they do not believe the man who shot and killed a Black man and woman in Winthrop Saturday was working with others, but they are still investigating how he was “radicalized” into attacking and executing people in what is being investigated as a hate crime.

Nathan Allen, 28, of Winthrop, shot and killed retired state trooper David L. Green, 58, and Air Force Staff Sgt. Ramona Cooper, 60, after stealing a box truck and crashing it into a building Saturday afternoon, officials said. Investigators allegedly found racist and anti-Semitic writing from Allen, who allegedly called whites “apex predators.”

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On Monday, Suffolk District Attorney Rachael Rollins said local officials have been working with the FBI while investigating Allen, and found racist writings in his hand dated as recently as last week. She said community members have been worried about other potential attacks, but she emphasized she believed Allen was acting alone.

“We understand people are very afraid he was working with other people, at this stage of the investigation we are confident we don’t believe that to be true,” Rollins said. “I am confident in saying there was hate in this man’s heart … when he became radicalized, when he started believing these things, we are not certain yet.”

Allen was later shot by a Winthrop police sergeant. He was pronounced dead at the hospital.

Sunday afternoon, officers were again called to Allen’s home after receiving eports of a suspicious package that was left outside.

Winthrop officials said they would hold a neighborhood drop-in meeting at the Winthrop Senior Center on Wednesday to address trauma in the community, and would hold a vigil for Cooper and Green on Thursday at 7 p.m.

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