Officers responded to the home on the night of May 24, 2023, after the baby went into cardiac arrest.
When officers arrived, the baby was not breathing and cold to touch, according to investigators.
The child was taken to an area hospital where he was pronounced dead.
Doctors say the baby suffered several injuries, including contusions, bruising and abrasions throughout his body. The doctor also noted that the injuries were indicative of a battered child.
According to the Bucks County District Attorney's Office, the child's father, 30-year-old Tyler Sullivan, violently shook the baby on at least two occasions on May 24, 2023, and at least six additional times in the six weeks prior.
Sullivan pleaded guilty on Wednesday to third-degree murder and endangering the welfare of a child.
His sentencing is scheduled for August 27.