Sawyer Paige Jefferson was left alone in the care of Cody Johnson, her mother’s boyfriend, who reportedly raped the 16-month-old girl.
The attack left Sawyer Paige’s body, including her face, covered in bruises, and both her vagina and rectum were damaged and bleeding.
When her mother came home and discovered her baby’s injuries, Johnson claimed that the child had "slipped on her pyjamas and fell on a toy”.
The child's mother rushed her to the emergency room at Saint Francis in Tulsa, USA, where the hospital staff said they immediately realised that Johnson’s story was a lie.
Sawyer Paige, who went into cardiac arrest, had to be placed on life support - and, after approximately two days, the infant tragically passed away.
Johnson was initially arrested on charges of child abuse and child sexual abuse. However, following the girl's death, police have now added a first-degree murder charge.
Corporal Greg Smith, of the Tulsa Police Department, called it one of the worst child abuse cases he has ever encountered, reported NewsOn6.
"We've seen some pretty badly beaten and abused kids over the years, but this one's pretty bad. I mean, it is pretty bad," he said.
Sawyer Jefferson’s mother is not facing any charges in the case because police say they have no reason to believe she knew about the abuse.
“Often times, we find these type of situations where we find some volatility in these relationships, maybe domestic issues, but I don't know of any in this case," Corporal Smith said.