A 19-year-old student suspected of fatally shooting his parents at a Central Michigan University dormitory had been acting so strangely the day before the killings that campus police talked to his mother and then took him to a hospital for suspected drug abuse, authorities said Saturday.

University police Chief Bill Yeagley told reporters that 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. 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.

Yeagley would not say whether the father had brought the gun to the university’s campus in Mount Pleasant, Michigan, when picking up his son, but he noted that Davis Jr. can be seen on video in the dorm’s parking lot with the gun before he entered the residence hall where his parents were shot around 8:30 a.m.

“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,” Yeagley said.

He declined to say whether drugs were found in Davis Jr.’s system. He also would not say what type of gun was used or whether it was Davis Sr.’s service revolver. But he did say that it would have been a violation of campus policy for Davis Sr. to bring a gun on campus because only law enforcement on active duty or those with special permission can do so.

Davis Jr. was arrested shortly after midnight following an intensive daylong search that included more than 100 police officers. Authorities found him after someone aboard a train spotted a person along railroad tracks in Mount Pleasant and called police, Yeagley said.