A judge declared a mistrial Monday in the murder trial of an Alabama teenager accused of killing his father, stepmother and three young siblings after new evidence from one of the victim’s cellphones became available.

Attorneys need time to review a “voluminous” amount of material that was contained in the phone belonging to the stepmother of defendant Mason Sisk, who was 14 at the time of the gunshot killings, Limestone County Circuit Judge Chadwick Wise wrote in a one-page decision.

Wise granted a defense motion to end the trial, which was entering its second week, and send jurors home. A second trial will begin Feb. 13, a court docket showed.

Prosecutors accuse Sisk, now 17, of shooting his family to death in their north Alabama home in 2019, saying he told investigators he killed them because he was “fed up” with them. Prosecutors argued that Sisk told a teacher he wouldn’t be in school the following week and then took a handgun from the home of a family friend to shoot his family.

Defense lawyers, who lost a bid to prevent jurors from hearing about Sisk’s statements to police, argued the boy didn’t have a plan to kill or any firearms experience.

Sisk was charged as an adult with multiple counts of capital murder, but he can’t be sentenced to death if convicted because of his age at the time of the slayings.

John Wayne Sisk, 38, and Mary Sisk, 35, were found dead in their home in Elkmont on Sept. 2, 2019, along with their three children — 6-year-old Kane, 4-year-old Aurora and 6-month-old Colson. All had been killed with gunshots to the head, authorities said.

Information from Mary Sisk’s cellphone became available to both sides during the trial, the judge wrote. The defense argued that messages in the phone showed a loving relationship between the woman and Mason Sisk, but prosecutors said the messages didn’t help the defense.

In ordering a mistrial, Wise said prosecutors didn’t cause the mistrial and it wasn’t immediately clear why the phone data hadn’t been released earlier.

Sisk initially told police he was in the basement playing video games when he heard gunshots and ran outside to see a vehicle pulling away, but he later told investigators he’d killed the five, prosecutors said.