A student suspected of shooting his parents dead at a university dormitory acted so strangely the day before that campus police talked to his mother and took him to a hospital for suspected drug abuse.
University police Chief Bill Yeagley said James Eric Davis Jr's parents had just picked him up from that hospital and brought him to his dorm to pack up for spring break when Friday's shooting happened, said university police chief Bill Yeagley.
He said the gun used in the shooting belonged to Davis' father, James Davis Sr, a part-time police officer in the Chicago suburb of Bellwood.
Central Michigan University is considered a gun-free zone, and Mr Yeagley said it would have been a violation of campus policy for Mr Davis Sr to bring a gun on campus.
"We can make a lot of assumptions, but I'm not going to make those assumptions. But I can tell you for sure that the gun came from outside, in the parking lot, with (Davis Jr) through the building," said Mr Yeagley.
Davis Jr was arrested without incident shortly after midnight following a day-long search that included more than 100 police officers, some heavily armed in camouflage uniforms.
Authorities found him after someone aboard a train spotted a person along railroad tracks in Mount Pleasant, and called police.
Mr Yeagley said Davis Jr was under guard at a hospital on Saturday and would be moved to the Isabella County jail when he is discharged.
Mount Pleasant is nearly 300 miles from the family's hometown of Plainfield, Illinois. The shooting occurred on a day when parents were arriving to pick up students at the university for the start of a week-long spring break.
He said police first came into contact with Davis Jr on Thursday morning when he ran into a community police officer's office in his dorm "very frightened" and but "not making a lot of sense."
"He said someone was out to hurt him, someone was going to harm him, and the officer calmed him down and tried to gain more information about what was going on. ... Mr Davis was very vague and he kept talking about someone having a gun," said Mr Yeagley, adding that Davis Jr said he had not actually seen the person with a gun.
"We said, 'How do you know he was going to hurt you if you didn't see a gun?' He was saying things like, 'It's just a feeling. I know it,'" the chief said.
Davis Jr eventually talked about riding in a dorm elevator with the person, and police went to talk to the individual Davis Jr had identified.
Mr Yeagley said when officers determined that the person posed no threat - and reviewed video from the elevator that showed Davis Jr and that person laughing - Davis Jr said he was fine and was leaving campus on Friday for the spring break.
Hours later, officers spotted Davis Jr in a dorm hallway with his suitcases. When officers tried to talk to him, he again was not making sense.
They asked Davis Jr to call his parents, which he did. An officer spoke to Davis' mother, Diva Davis, told them about her son's behaviour, their concerns about possible drug use and asked her whether he had a history of drug use, Mr Yeagley said.
"The mother said she too was concerned this could be drugs," he said.
Police released a photo of Davis Jr after the shooting and urged the public to call 911 if they saw him but warned that he should not be confronted.
Yeagley said Davis Jr was not previously identified by campus officials as someone that others on campus were concerned about.
"Mr Davis was not ever reported, and we had no interaction that we're aware of with him in any negative fashion - with anybody - prior to this incident," he said.
University president George E Ross said the shooting left the campus and surrounding community traumatised.
"There were thousands of people who were sheltering in place yesterday and they will be dealing with this for the rest of their lives," he said.