OKLAHOMA CITY - A metro man is in the Oklahoma County Jail accused of abusing his girlfriend’s four-month-old baby.

Police arrested Antonio Goodwin,31, last Friday on a complaint of first degree murder. Doctors told investigators the infant, Ryan Keesee, died from head trauma.

Oklahoma City Police were called to Deaconess Hospital on Friday, April 6, after being notified that Keesee was admitted and did not have a heart rate.

Goodwin told hospital staff he was the baby's step-father.

“The victim was actually under the care of Antonio Goodwin at the time when he received his injuries,” said Officer Megan Morgan, Oklahoma City Police Department.

Goodwin told investigators he was watching his girlfriend's baby and two other children at their northwest Oklahoma City apartment while she went to work.

Goodwin said he heard the baby crying in a bedroom. When he went to check on the infant, he said, he saw the boy's two-year-old sister standing on his back in a playpen. Goodwin said he later noticed discoloration of the baby's skin and heard him whimpering.

“The child unfortunately later succumbed to his injuries around 2 p.m. that afternoon,” said Morgan. “It was determined the injuries the child had were consistent with signs of child abuse.”

Baby Keesee was taken to OU Children's Hospital where doctors told investigators the baby had significant head injuries, including skull fractures and bleeding on the brain.

Court papers also revealed there were no marks or injuries visible that would be consistent with a child standing on the baby.

Police arrested Goodwin in connection to the baby's death.

Goodwin also told police he left the apartment for about 10 minutes that day to go to the store. He said all three children, including the baby, were asleep while he was gone.