A 17-year-old Massachusetts boy who allegedly used ChatGPT to explore fantasies about killing his family is accused of murdering his mother and younger brother inside the family's home in an affluent Boston suburb and was ordered held without bail Thursday as prosecutors revealed new details about the violent scene.

Arjun Aravind, of Acton, was arraigned Thursday in Concord District Court on two counts of murder, two counts of assault and battery with a dangerous weapon and two counts of assault and battery, the Middlesex District Attorney’s Office confirmed to Fox News Digital.

He was charged as an adult under Massachusetts law, and he pleaded not guilty, the DA’s office said.

Middlesex District Attorney Marian Ryan said Wednesday that investigators uncovered what she characterized as "concerning behavior" by Aravind in the period before the deaths, including internet activity and the use of ChatGPT to explore theoretical or fictional scenarios involving the killing of his family.

Ryan said Aravind allegedly used the artificial intelligence chatbot to "make searches including for theoretical ideas or fantasies regarding killing his family."

The teen is accused of murdering his mother, Sudha Venkatesan, 45, and his 14-year-old brother, Siddharth Aravind, who were found dead Tuesday evening inside the family’s Martha Lane home.

Acton is an affluent community about 30 miles north-west of Boston, and the family had recently moved to the town in part for its schools and a support system for the children, Aravind’s defense attorney, Debra DeWitt, told mental health evaluation. When the judge asked whether the request concerned Aravind’s competency to stand trial or his potential criminal responsibility, DeWitt said that had not yet been determined.

Aravind is due back in court Sept. 11 for a probable cause hearing.

Fox News Digital has reached out to OpenAI for comment.