Ian Moore, a 31-year-old worker at Kid's Country day care in Normandy Park, Washington, was arrested last Friday for allegedly sexually assaulting a little girl.
Moore was taken into custody after the 5-year-old's father walked in on the caregiver and his daughter "crouched behind a bookshelf," detectives told the local Fox affiliate.
Moore reportedly told the girl's parent they were having a "tickle fight." The girl later said that he had touched her private parts, which Moore admitted when questioned by police, but said it was an accident.
According to Q13Fox, court documents said that Moore said "when he slipped on a toy as he was tickling" the girl, his fall "caused his hand to slide into her panties and penetrate" one area of her genitals while touching another.
"Even after I tried to explain to Ian that his version of events was virtually impossible, he continued to claim that was how it had happened," the detective wrote.
Moore has been charged with first-degree child molestation and is being held in the King County Jail in lieu of $200,000 bail.
The suspect's grandmother said she was devastated when she spoke to the news station.
"It's hard to believe it's true," she said. "He was raised in a good environment. We don't know of any reason [why] this is happening. I am very, very sorry if this is true … Please forgive us. I am crying for everybody, I am crying for the little girl, I am crying for our family."
BuzzFeed News has reached out to the King's County Sherrif's Office for comment.