AYER, Mass. (AP) — Authorities say a baseball bat was found on the property of a Massachusetts home where officials say a recent college graduate killed his mother, his grandparents and a caregiver.

Middlesex District Attorney Marian Ryan told reporters Monday that the bat "may have been used" in the killings Friday in Groton (GRAH'-tun). Ryan said the victims appeared to have died of blunt force trauma.

Twenty-two-year-old Oberlin College graduate Orion Krause, of Rockport, Maine, was ordered held without bail at Bridgewater State Hospital pending a competency hearing at his arraignment on murder charges Monday in Ayer.

Ryan identified the victims as 60-year-old Elizabeth "Buffy" Krause, 85-year-old Elizabeth Lackey, 89-year-old Frank Lackey III and 68-year-old Bertha Mae Parker.

Ryan says Parker was a health service provider for Krause's grandparents.