Cambridge Police report a security guard at a Harvard Square bank faces a charge of larceny from a building for an incident around 2 p.m. yesterday.
According to police, the guard noticed a customer had left an envelope on a teller counter and decided to take it.
He later returned the same envelope to the assistant bank manager, which he claimed to have found. A short time later, the customer/owner of the money reported to bank personnel that they were missing $400 from the returned envelope.
Police say the theft was recorded by a surveillance system at the bank, which they did not name, but said was in Brattle Square.