Police say 1-year-old Shawn was rushed to the hospital after suffering severe head and abdominal injuries back in March of 2009.
Coles was watching the child when the child was injured and Coles originally told police it was an accident.
Since then, Coles has changed his tune and today pleaded "no contest" to first-degree felony murder, which still results in the finding of guilt under criminal law.
The judge accepted Cole's plea and sentenced him to 30 years in prison.
"This is a long time coming on this case as you heard in court the offense date was in 2009," said Deputy District Attorney Sunshine Staneck. "We've had many conversations with the victim's family and we felt like the 30-year sentence on the murder was an appropriate sentence in this case and is justice in this case."
Coles will be eligible for parole in 15 years, but Staneck said due to his age and the nature of this case it's unlikely he'll ever walk.
In 1986, Coles was arrested for a similar crime in the death of his 1-year-old stepson but was never charged.