FORT WORTH (CBS 11 / TXA 21) Police say Ryan Durham, 19, was watching his fiancée's 2-year-old at their home in the 2900 block of Spencer Street.
Durham told police the child, Robert Philbin, fell off the toilette last Wednesday, but investigators aren't buying it.
The incident happened after the toddler's mother, along with Durham's stepfather, had left for work.
Neighbors say they didn't know the family very well but they are shocked about what's happened.
"I wish we would have known that they were hurting over there we could have offered to help maybe," next door neighbor Jon Leep said. "That makes me so sad; it's just next door."
According to the medical examiner's report Robert had a fractured skull, bleeding and swelling in the brain and retinal injury. He was rushed to Cook Children's Medical Center, but died there a day later.
"The explanation given by Mr. Durham simply didn't add up. When you look at injuries child sustained they are inconsistent," explained Sgt. Chad Mahaffey with the Fort Worth Police Department.
Department of Public Safety records show that Durham is a paroled sex offender who was sentenced in September, 2003 for Indecency with two children; one a 7-year-old girl and the other a 6-year-old boy.
"Part of his conditions did not restrict him from being near the 2-year-old, consequently he's the only one facing charges in the case," says Mahaffey.
Neighbors finding out about Durham's sex offender registration say they always had a bad feeling about the family