MINNEAPOLIS (WCCO) – A 19-year-old St. Paul woman faces murder charges in the death of a 5-month-old boy she was babysitting last week.

Tyanna Jabree Graham is charged with one count of second-degree murder, court documents filed in Ramsey County show. If convicted, she faces up to 40 years in prison.

According to a criminal complaint, St. Paul police responded early Saturday morning to a report of a baby not breathing at a home in the city’s Highland neighborhood. The child was rushed to Children’s Hospital, where doctors found the boy to have suffered severe brain injuries that did not appear to be accidental.

Graham, who called 911, told officers that she had been caring for the child since Thursday, as his mother was in Wisconsin for work, the complaint states. She said the child fell off a couch Friday evening and started to cry overnight.

The child died Sunday. The Ramsey County Medical Examiner determined the boy’s death was caused by traumatic head injuries due to a physical assault. The criminal complaint says “classic findings” of abuse were found on the boy’s body, such as bruises on his lung and a cut under his upper lip.

In an interview with authorities, Graham changed her story several times, the complaint states. Among the various stories, Graham told police that she was upset she had to watch the child when she wanted to go out and became mad when he wouldn’t stop crying.

In one of the stories, she said that when she got mad, she “blacked out” for two minutes and when she came to again the boy was on the floor.

Graham is currently in custody. Her bail has been set at $1 million.

Ramsey County Attorney John Choi called the boy’s death an “unthinkable tragedy.” He added that caregivers can reach out for counseling by contacting the Greater Minneapolis Crisis Nursery.