OMAHA, Neb. (AP) — A northeastern Nebraska man has been sentenced to eight years in federal prison for causing the death of his girlfriend’s 14-month-old son.

The U.S. Attorney for Nebraska says 22-year-old Mark Grant, of Winnebago, was sentenced Thursday in U.S. District Court in Omaha after being convicted of one count of child abuse causing death.

Court documents say Grant was caring for Julius Harlan on Sept. 10 when the boy suffered severe brain injuries and died the next day at an Omaha hospital.

Investigators say Grant was the only person with the child when the boy received the injuries and that Grant told different stories about the circumstance behind the boy’s injuries.