Maria Elena Sullivan, 26, is facing a charge of murder and three counts of child abuse in connection with the September 17 death of her 13-day-old son.
Prosecutors allege Sullivan's boyfriend, 21-year-old Dylan James Kitzmiller, was regularly abusing the infant and Sullivan knew about the abuse, but did nothing to stop it.
"This was just people who were handling this child very roughly, but the level and severity of injuries that were there were quit severe. And what the doctors recognized was this was not something that was the cause of accidental conduct," said Salt Lake County District Attorney Sim Gill.
Court documents allege the rough handling included throwing the infant in the air, slapping, biting and covering his mouth and nose. A statement of probable cause indicates the infant lost 14 percent of his body mass in the 13 days he was alive, and that he suffered numerous bruises, abrasions, broken bones and injuries to his brain and spinal cord.
Sullivan was arrested at a hospital in Georgia and extradited to Utah, then booked into the Salt Lake County Metro Jail on Thursday.
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