Watertown Police received a call on Sept. 30 at 3:23 a.m. from a concerned driver who had spotted a speeding car that appeared to have damage from an accident.
The driver saw a Toyota driving over the limit on the Mass Turnpike and it appeared to have struck the guard rail or another car, said Watertown Police Lt. Michael Lawn.
The good samaritan followed the car off the Pike, and into Watertown, where it stopped on Westminster Avenue, Lawn said.
Police arrived and when the officer spoke to the driver he detected an odor of alcohol on the man's breath, Lawn said.
Nuno P. Arruda, 40, of 130 Westminster Ave. in Watertown, was arrested on a charge of driving under the influence of alcohol, Lawn said.