A Baton Rouge man's conviction and life prison term in the 2011 beating death of his girlfriend's toddler has been upheld by the Louisiana Supreme Court.

Randy Demond Parker, 29, was found guilty in 2015 of second-degree murder in the killing of 23-month-old Demarcus Gray Stokes Jr.

Parker beat the child because he would not sit still for a haircut and after he urinated on himself, authorities said.

An autopsy revealed bleeding under the boy's scalp and on the surface of his brain, and a considerable amount of bruising on his head, torso, arms and legs.

The child's mother, Kimyia Stokes, 28, is serving a 20-year prison term for obstruction of justice. She pleaded guilty to that charge in 2015.

Stokes told investigators that Parker beat her son three times in less than 24 hours in October 2011 at Parker's Erie Street home. She said she witnessed two of the beatings and heard her son screaming during the third.

Stokes also told police she and Parker dressed the boy after he stopped breathing and "waited around trying to figure out what to do and say" before Parker finally called 911.

Parker told detectives he was "full of alcohol" the night he punched Demarcus with a closed fist and continued to hit the boy after he fell to the ground.

Parker was tried on a first-degree murder charge, but prosecutors chose not to seek the death penalty after receiving evidence that he was possibly intellectually disabled. The U.S. Supreme Court has prohibited intellectually disabled inmates from being executed.

State District Judge Trudy White found Parker guilty of second-degree murder and sentenced him to a mandatory term of life behind bars.

The state Supreme Court affirmed his conviction and sentence on Friday without issuing reasons. A state appeals court upheld the conviction and sentence in February, saying Demarcus had been "severely abused."

East Baton Rouge Parish District Attorney Hillar Moore III said Tuesday that the state's high court made the right call in affirming the Parker's conviction and sentence.

"Our office put in a tremendous amount of work into this case and we believe that the jury's verdict and decision of the Supreme Court have brought justice for Demarcus Stokes Jr.," Moore said.

Parker had previously been convicted of attempted second-degree murder and simple assault.

Follow Joe Gyan Jr. on Twitter, @JoeGyanJr.