UPDATE: Babysitter charged with 1st-degree murder after 2-year-old dies

MEMPHIS, Tenn. —  A two-year-old boy was rushed to Le Bonheur Children's Hospital in extremely critical condition after police say the man who was supposed to be watching him abused him.

By Friday afternoon, police said the boy had died.

Alan Johnson was taken into custody and originally charged with aggravated child abuse. Friday morning, a charge of first-degree murder was added.

First responders arrived in the 3200 block of Kings Arms Street in Fox Meadows on Wednesday evening to find the little boy unresponsive and not breathing.

As an ambulance rushed the boy to Le Bonheur, officers said they spoke with the man who was looking after him that evening, Alan Johnson.

Johnson told police he was throwing the boy into the air and then catching him for fun. On the last throw, he said the boy slipped. He grabbed the child by the ankle and swung him around trying to keep him from hitting the ground.

He said when he made the movement, the boy's head snapped back and he became unresponsive.

But doctors later told police the man's story was inconsistent with the boy's injuries. The two-year-old had a skull fracture,  swelling of the brain, injuries to his liver and kidneys, stomach bruising, front and back rib fractures, and rectal bleeding.

Johnson's relationship to the baby is not clear. A neighbor said she’s never seen a baby at the home before. She knows Johnson and his wife but says they have a teenage daughter.

"He always seemed pleasant. He always waved,” the neighbor said.

But Shelby County records show Johnson has been in trouble with the law before. Just last year, police charged him with aggravated assault, saying he pointed a gun at another driver in a fit of road rage.