A 67-year-old Deer Park woman was defrauded of $359 when an unidentified caller who claimed he represented Microsoft offered her a refund on a service package he said she had bought many years previously, the Napa County Sheriff's Office reports.

The woman, who was not identified, reported the theft this week. She said the man called her on Dec. 19 and offered to help her transfer money via Western Union online so she could receive the refund directly. She became suspicious and eventually hung up, but not before entering her bank account and routing numbers, Capt. Doug Pike said.

She subsequently discovered that someone had removed $359 from her account. The bank told investigators the thief attempted two other transactions — for $307 and $507 — but they were flagged as suspicious and blocked, Pike said.

While financial scams are common, Pike said, this is the first time the Napa Sheriff's Office has seen this particular technique. He advised people to be cautious when giving out personal information to unknown callers.