People who had contact with the letter at Princeton Borough Hall yesterday reported blisters and rashes. They received precautionary treatment at the scene but weren't taken to a hospital.
Police Lt. David Dudeck says he's sure it was a false alarm.
There were about 30 employees in the building at the time. No one had to be decontaminated.
The building was evacuated and workers were sent home.
The letter was sent by a 70-year-old resident of a Louisiana nursing home who is confined to a wheelchair. An official says the man suffered some kind of brain trauma and believed he could get help from a research center in the area. Police haven't released his name.
