On Feb. 29, Barbera called 911 and, according to prosecutors, confessed to the crime. He then attempted to commit suicide by slicing his throat with a razor blade. By the time emergency services personnel transported his mother to Northridge Hospital, she was incoherent.
A medical examination of the victim revealed previous rib fractures as well as new injuries.
The victim, who worked as a registered nurse at Northridge Hospital for 25 years, died on March 14 as a result of the attack.
Barbera faces a maximum prison term of 15 years to life, according to prosecutors.