Bronx-Lebanon Hospital officials say the doctor who was killed in Friday's shooting was not scheduled to be at work when Henry Bello opened fire.

They say that 32-year-old Dr. Tracy Sin-Lee Tam, of Queens, was filling in for a colleague the day of the incident.

According to an online profile, Tam finished medical school in 2013 and had been working in the hospital's Department of Psychiatry for almost a year. Her neighbors say she was a quiet, but friendly woman.

It is still unclear whether Tam knew the gunman or if she knew that his intended target was Dr. Kamran Ahmed, a physician who was not at work that day.