Authorities began searching for the couple after Oakland County prosecutors said on Friday that they would be charged with manslaughter in connection with the campus mass shooting.

Jennifer Lynn Crumbley and James Robert Crumbley, parents of Oxford High School shooting suspect Ethan Robert Crumbley, 15, appear from Oakland County Jail in Pontiac, Michigan, U.S.

Four days before the shooting, Ethan accompanied his father to a gun shop, where James Crumbley bought a 9mm handgun, prosecutors said.

The next day his mother posted that the two of them were at a gun range "testing out his new Christmas present," Oakland County Prosecutor Karen McDonald said.

21, a teacher found Ethan Crumbley searching for ammunition on his phone and alerted school officials, who left messages for his mother that went unreturned.

On the morning of the shooting, a teacher discovered drawings by Ethan Crumbley that depicted a handgun, a bullet, and a bleeding figure next to the words "Blood everywhere," "My life is useless," and "The thoughts won't stop - help me.".

School officials summoned the Crumbleys and instructed them to get Ethan into counseling within 48 hours, McDonald said

Ethan Crumbley was returned to class and later walked out of a bathroom with the gun, killing four students and injuring seven other people, authorities said