A Massachusetts teen accused of killing his mother and brother allegedly used artificial intelligence to make searches for "theoretical ideas or fantasy stories regarding the killing of his family," according to the Middlesex District Attorney's Office.

17-year-old Arjun Aravind of the affluent bedroom community of Acton was arrested Wednesday, a day after the bodies of his mother and teen brother were found in their home.

The victims have been identified as Arjun's 45-year-old mother, Sudha Venkatesan, and 14-year-old brother, Siddharth Aravind. Ryan said both of them were "suffering from obvious trauma," though the exact causes and manners of their deaths will be determined by the Office of the Chief Medical Examiner.

Arjun Aravind is facing murder and assault charges.

"The investigation has so far shown that Arjun had recently been demonstrating some disturbing behavior including using the internet and ChatGPT to make searches for theoretical ideas or fantasy stories regarding the killing of his family," Ryan said.

Middlesex County District Attorney Marian Ryan said 17-year-old Arjun Aravind is unaccounted for, asking anyone who sees him not to approach him and to call 911.

Ryan said the investigation began as a welfare check, when Aravind's father called police to report he couldn't reach anyone at the home, which was unusual.

When police arrived they found both victims dead in the home — Venkatesan in the finished basement, and Siddharth on the first floor.

Aravind was unaccounted for, and investigators believed he fled in his mother's car.

Law enforcement put out a BOLO for that green 2014 Honda Accord with Massachusetts plates reading "34PD94." The vehicle was found overnight in nearby Wayland, with Aravind inside. The car was later towed back to the Acton Police Department.

A vehicle tied to a death investigation in Acton, Massachusetts, found in Wayland.

In an update around 9:20 a.m. Wednesday, the district attorney's office confirmed that Aravind had "been located and there is no risk to public safety."

He was expected to be arraigned on two lesser charges — use of a vehicle without authority and theft of a motor vehicle — in Lowell Juvenile Court Wednesday afternoon. He is set to be arraigned on the murder charges at Concord District Court on Thursday.

"As you can imagine, we're certainly trying to reach other members of the family," Ryan said Tuesday. "People are trying to struggle to come to grips with what happened up there."

Acton Public Schools Superintendent Peter Light issued a statement on the situation:

"This is obviously a horrific and tragic situation on many levels, and we are heartbroken for the family, friends, staff and others impacted by this. Our thoughts are focused on the students, their family, friends, and our staff. We have no further information to share about the incident or investigation.

We have a plan in place, including counselors at the schools, to support students and staff during this difficult time. Our schools will communicate directly with families about the details of the support available to students. Our school mental health staff will be providing ongoing assistance to anyone who needs it. Again, our hearts go out to all of those involved with this tragic situation."

This story originally appeared on NBCBoston.com.