BEAVER, Utah (ABC4) – A mother in southern Utah has been arrested for allegedly shaking her infant child to death in September.

In mid-September, authorities were called for an infant not breathing in Beaver, about 104 miles north of St. George. Medical personnel arrived and took the baby to a nearby hospital, where the infant was pronounced dead at just 23 days old.

Investigators spoke with the child’s father and his fiance, later identified as 32-year-old Tawna Steed. According to the father, only he and Steed had been with the child except for “one or two times since the child was born.”

Following the autopsy, the pathologist informed the Beaver County Sheriff’s Office the infant’s manner of death was a homicide. The child had multiple healing rib fractures that occurred on at least two different incidents, the arresting affidavit reads. Additionally, the infant had at least two separate brain hemorrhages. Authorities say that would have occurred by someone shaking the infant or some other type of blunt force trauma causing death.

In mid-October, the Beaver County Sheriff’s Office again spoke with the child’s father about the autopsy findings. In response, the arresting affidavit says he denied hurting or killing his child and “was very emotional at times, crying and putting his head into his hands.”

When investigators spoke with Steed, they say she also denied hurting or killing their child. Authorities noted in the arresting affidavit that Steed “never cried or became upset during the interview.” When Steed asked for an attorney, the Beaver County Sheriff’s Office placed her under arrest and booked her into jail on one count of aggravated murder.

Authorities say they again spoke with the infant’s father who “became very emotional, crying and leaning over putting his head into his hands.” He told investigators he had seen Steed shake the child twice. The first time, he says he had heard the baby crying for a while and when he came into the apartment, she was sitting on the bed holding the infant in front of her.

The father says Steed “was shaking the baby vigorously and grabbing it tightly across the chest with her two hands.” She was allegedly yelling at the infant, telling it to stop crying. The father tells investigators he took the infant away from her. He described the child as being stunned but “got better” when he took it outside.

The second time, the man says he walked in and saw Steed shaking the child again. Again, the man says he took the child and comforted it. After both times, he tells the Sheriff’s Office he took the child to his parents’ house.

Steed was booked into the Beaver County Jail on one count of aggravated murder.