BIDDEFORD, Maine (AP) — A Massachusetts man who beat his partner to death on a beach in Maine was sentenced Wednesday to 40 years in prison.

Jeffrey Buchannan had pleaded guilty to murder under a plea agreement. He told police he blacked out before the attack on Rhonda Pattelena, who was bludgeoned with a rock on Short Sands Beach in York on March 26, 2021. Buchannan was arrested after police received multiple 911 calls that day.

Pattelena, 35, wanted Buchannan to see her favorite beach, her family said.

She was sending a Snapchat video to a friend while on the beach when she was first struck, prosecutors said. Some of the assault also was captured on a surveillance video from nearby businesses, according to police.

Police collected evidence from the scene including the rock, which was displayed to the judge in court on Wednesday.

The defense contended 36-year-old Buchannan, from Bedford, Massachusetts, was experiencing a psychiatric crisis.

Buchannan’s guilty plea came under an agreement with prosecutors that capped his sentence at 43 years. Pattelena’s friends and family urged the judge on Wednesday to impose a sentence greater than that.

Pattelena was already dead when police arrived; an autopsy concluded she died from head injuries. The two were domestic partners and had one child together, the youngest of Pattelena’s three children. None of the children were present during the attack.