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Prosecutors filed a murder charge Monday against a Murray baby sitter accused of shaking a 4-month-old baby to death.

Jennifer Duran Martinez, 35, had been watching Kaysen Calhoun for less than two hours when she became frustrated because he would not stop crying, according to charging documents filed Monday in 3rd District Court.

Martinez admitted to police she "picked him up and violently shook his head back and forth for an extended period of time," prosecutors wrote. When she stopped, Martinez saw Kaysen wasn't breathing and called 911.

When police responded, an officer couldn't find a pulse. Kaysen was rushed to Primary Children's Medical Center, where he was put on life support until he was pronounced dead at 6:45 p.m. Doctors said he was killed by a skull fracture and brain swelling, according to charging documents.

He also had rib fractures that were healing at the time of his death, prosecutors said.

Martinez was a neighbor and acquaintance of the child's mother, who dropped the baby off at Martinez's apartment at 4638 South Urban Cove about 3:30 p.m. on Sept. 22. The baby had a cold but was otherwise healthy when she left him with Martinez, according to the charges.

Martinez now faces a single count of murder, a first-degree felony.