Orion Krause twice told his former professor at Oberlin College that he believed he had to kill his mother, a grim warning provided to Maine police the same day he allegedly killed his mother, his grandparents, and a health care aide in Groton, Mass., a police report indicates.

Krause, 22, allegedly killed the four people on Sept. 8 with a baseball bat and then went to a neighbor’s house, naked and spotted with blood and mud, where he confessed that he had just killed his family.

Groton police responded to the Common Street area around 5:52 p.m. that day, records show.

About 45 minutes earlier, the wife of Oberlin professor Jamey G. Haddad had contacted police in Rockport, Maine, Krause’s hometown, according to a Rockport police report.

“I think I have to kill my mom,’’ Krause twice told Haddad, according to the report. Haddad’s wife, Mary K. Gray, relayed the conversation to Sergeant James C. Moore of the Rockport police. She said her husband had asked Krause to repeat himself to make sure he heard correctly.

“Gray stated that [Haddad] had received a call from Krause and he did not seem like himself,’’ Moore wrote in his report. “Krause stated to Haddad twice during the conversation ‘I think I have to kill my mom.’ ’’

Krause graduated from Oberlin this year. The Portland Press Herald first reported the phone conversation.

As he spoke with Gray, Moore recalled that Krause’s worried mother, Elizabeth, had called his department about her son the day before, six hours after he drove away from their home. She was worried that he might take his own life, the Globe reported Thursday.

“We told him that the world wants him alive, and he did promise that he wouldn’t do it, and so I am trying to have faith,’’ she said, according to a transcript of the call. “I’m just concerned and I’m scared.’’

In his report, Moore said that, after recalling the interaction with Elizabeth Krause, he called Orion’s twin brother, Cooper, who provided the telephone number for his grandparents’ home in Massachusetts, where he believed his mother was visiting. Cooper Krause said he did not know what town his grandparents lived in, according to the ­report.

Moore tried telephone numbers for Elizabeth Krause and the grandparents, but no one picked up. He Googled the grandparents’ telephone number and learned they lived in Groton, a town near the northern edge of Massachusetts.

Moore called Groton police, identifying himself as a Maine police officer.

“I was immediately asked if this was about Orion Krause,’’ Moore wrote. “I was advised this was the fifth call in relation to Orion . . . officers were at the scene.’’

Moore hung up.

Elizabeth Krause and her parents, F. Danby Lackey III, 89, and Elizabeth Lackey, 85, were found dead inside the Groton home. The body of Bertha Mae Parker, 68, the caretaker who looked after the Lackeys, was found outside in a flower bed, police said.

Orion Krause has pleaded not guilty to four counts of murder.

He has been found competent to stand trial but has been sent to Bridgewater State Hospital, a psychiatric facility run by the state prison system, while his case is pending. Court records show that Krause has been administered antipsychotic medications since his arrest.

John R. Ellement can be reached at ellement@globe.com. Follow him on Twitter @JREbosglobe.