Mug shot of Isaiah Sweet, accused in the murder of his grandparents in Manchester.

A teenager charged with first-degree murder told investigators he first considered hitting his grandfather with a baseball bat before deciding to shoot him and his wife instead, according to search warrants filed Friday in Delaware County District Court.

Isaiah Sweet, 17, of Manchester, is accused of killing Richard Sweet, 55, and Janet Sweet, 62, earlier this month in the home he shared with them.

Authorities have said they were last seen alive around 7:30 p.m. May 11. Family members arriving for a Mother’s Day visit on May 13 found the Sweets’ bodies on a living room sofa; each had been shot in the head, the warrant said.

Isaiah Sweet was captured the following day in Cedar Rapids. According to a criminal complaint, he’d told three witnesses over the weekend that he’d killed his grandparents.

Items removed from the home during the search included a spent rifle casing, ammunition and two knives, according to the search warrant.

The warrant also says Manchester police had been called to the family’s home in the past for reports of verbal and physical abuse. No further details were available.