WESTLAND, Mich. -

A Westland father has pleaded guilty in the beating death of his infant son while the mother has been referred for a competency exam.

Josh Wilson and his girlfriend Kelli Worth-McBride were charged after 3-month-old Joshua Jr. died in December.

Wilson had pleaded guilty to second-degree murder and is set to be sentenced on April 23.

Family members have said both parents suffer from mental issues and that Child Protective Services had been involved with the family since Joshua's birth.

Police say the infant had been severely beaten. He was taken to University of Michigan Hospital in Ann Arbor. He was bruised from head to toe with several broken bones. Investigators say Joshua died from blunt force trauma to his chest.