Over the weekend, authorities say someone broke into more than 30 postal boxes and swiped the mail inside.
Postal inspector Tracy Putnam is investigating the break-ins. Putnam says the suspect was likely after personal information, checks, or small parcels.
The owners of those P.O. boxes have been notified and asked to be on alert for suspicious activity involving their financial accounts.
"We're hoping that the people that the boxes got broken into can pass some information on to us," Putnam said.
Customers who heard about the burglary say they were surprised.
"You would think the post office box would be a safe place," said Judy Wiggins of Menifee.
The mail boxes are located in the lobby, which remains open to the public even when the post office is closed. But that could change. The post office is evaluating whether it needs to limit the lobby's hours.
"Some places where we have a higher crime rate or we have some previous histories, we close the facility down, it is not open 24-7," said Putnam.
Tampering with the mail is a federal offense; if the suspect or suspects are caught they could be facing a 5-year prison term along with a $5,000 fine.