Updated

Authorities say a Massachusetts nanny in the country illegally could be charged with murder after the 1-year-old child she was watching suffered fatal injuries in her care.

Aisling (ASH'-ling) McCarthy Brady is being held on $500,000 bail after pleading not guilty Tuesday to assault and battery on a child causing injury. Prosecutors say the charges against the Quincy woman could be upgraded after an autopsy on Rehma Sabir, of Cambridge.

Rehma was hospitalized Jan. 14 — her first birthday — with head injuries. She died two days later.

Authorities say Brady was the only person with the child when the injuries occurred. Brady's attorney says the injuries could have happened at any time.

Immigration authorities say Brady arrived from Ireland in 2002 and was only permitted to stay 90 days.