A 10-month-old baby girl died after being allegedly subjected to a sexual assault by her mother's new boyfriend in a downstairs basement. Emmaleigh Barringer was discovered injured by her mother, Amanda Adkins, police in Charleston, West Virginia say.

Following the alleged assault, the toddler was rushed to hospital in a critical condition, was placed on life support for several days before being declared brain dead.

Benjamin Taylor, 32, faces a murder charge, after being originally charged with first degree sexual assault.

Police believe the child's mother, Amanda Adkins, awoke around 5am local time to discover her daughter badly battered in the basement of the property both her and Taylor lived in.

It has been reported that she was bleeding with clothes and blankets covered in blood found nearby.

Jackson County sheriff's deputies arrested Taylor at the scene, who initially told officers that he did not know how the injuries happened.

The Charleston Gazette Mail reported that deputies claimed that he was seen trying to "vigorously" wipe something off his groin area when he was handcuffed by officers.

County Sheriff Tony Boggs said sexual assault charges against Taylor would be upgraded to murder. "The charges will be upgraded as soon as possible," Boggs said according to the newspaper.

"I don't know if that will be tonight yet or in the morning. But Mr. Taylor will be charged with felony murder sooner (rather) than later."

Boggs failed to suggest a motive for the alleged crime. "I don't know of any normal human that could fathom what would possess somebody to do that," he said.

"This investigation is ongoing, but as far as his past and what she did or didn't know, he didn't have anything obviously of this nature in his past, or he wouldn't have been out (of jail) period."

Amanda's cousin, Danielle Adkins, told WSAZ: "The only way justice is going to be served is if he feels every ounce of pain that he caused her too. It wasn't enough that he took her innocence, he had to take her life too."

She added that Taylor had swept Amanda off her feet. "You literally would have thought he was a Prince Charming, she [Amanda] was so lit up inside. He wanted to do things with her and he hung out with the kids."