JACKSONVILLE, Fla. -

Thursday morning, a Navy sailor stationed at Mayport, makes his first appearance in court. He was arrested Wednesday in connection with the 2010 beating death of his girlfriend's 2-year-old son. Nicholas Rivet, 35, is charged with one count of murder.

Police say Rivet and the child's mom kept changing their stories about what happened, but Wednesday morning he turned himself in. His head was hanging low and he was dressed in his navy fatigues, when homicide detectives escorted Rivet into jail Wednesday.

Rivet is based at Naval Station Mayport and has been in the Navy for 13 years. Investigators say he's responsible for the beating death of 2-year-old Eddie Robb in January of 2010.

"The investigation has taken so long because you had Nicholas Rivet and the mother of Eddie Robb contradicting each other, going back and forth about who was at fault," said Jacksonville Sheriff's Office Lieutenant Rob Schoonover.

"We investigated this case thoroughly and we did verify that abuse had taken place. What we could not determine was exactly who had abused Eddie," said John Harrell, spokesperson with Florida's Department of Children and Families.

According to the police report, the child's brain was bleeding, he had a fractured skull and a blown pupil when he was found unresponsive inside Rivet's mayport home. That's where police say he had been staying with his mom, a sibling and Rivet's two children.

The child's mother, Brandi Robb, told police she heard a "thud" come from the upstairs room where Eddie and another child had been sleeping. When she walked up, she claims Rivet was walking out of the room, saying Eddie had woken up his daughter, and was trying to get them back to sleep.

"He would come up to you and he'd bother you, hug you, kiss you until you started smiling until you started being happy," said Bert Robb, the child's father three years ago after Eddie died.

Rivet is being held without bond and is scheduled to make his first appearance Thursday morning.