TROY, Mich. -

A Troy man has pleaded guilty, but mentally ill, to his father's murder.

Patrick Mikes Jr. pleaded guilty Wednesday to second-degree murder for killing Patrick Mikes Sr.

He's scheduled to be sentenced on Sept. 10.

Patrick Mikes Sr., 55, was reported missing July 29,2012, by his two sons -- who said the father had left their home two days earlier for a bike ride and never returned home.

His body and his bike were found two days later in Genesee County’s Montrose Township.

Prosecutors said evidence in the family's home suggested the younger Mikes violently beat his father to death in their basement.

More coverage: The murder of Patrick Mikes