New court documents allege an Alabama teen accused of killing five family members was aggressive toward his relatives before the 2019 killings.

Local news outlets report that the documents say Mason Sisk, among other things, tried to poison his stepmother with peanut butter, stirring it into her coffee when he knew she had a severe peanut allergy.

Sisk has pleaded not guilty to capital murder charges in the 2019 deaths of his father, 38-year-old John Sisk; his stepmother, 35-year-old Mary Sisk; and their three children, 6-year-old Kane, 5-year-old Rorrie and 6-month-old Colson. All died from gunshot wounds at home in Elkmont while they slept.

Mason Sisk was 14 at the time of the killings. He is being tried as an adult. Investigators said the teenager called 911 to report the shooting and later admitted to killing his relatives after they questioned his initial story.

The documents say Sisk threatened his father and stepmother. It also says Sisk was forceful with his siblings at home and had “anger control” issues with his brother.

Prosecutors say Sisk stole two rings from his stepmother and gave them away and stole a gun from his grandmother’s house.

Although he faces capital murder charges, Sisk could not be executed if convicted because he was under 18 at the time of the killings.

Authorities have not publicly released a motive in the slayings but have said Sisk showed little remorse. Sisk could go to trial later this year.

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