A Sheriff's Department lawyer, Sanford Toyen, told The San Diego Union-Tribune the recordings were made because of an inadvertent glitch.
Defense lawyers called it eavesdropping, a felony and punishable by fines up to $5,000 per call. They are concerned that prosecutors --who could access the recording system from their computers -- could have gleaned information needed for convictions, the newspaper reported.
Attorney Jim McMahon of the county's Alternate Public Defender office said he found out that his calls with client Robert Crouse were recorded when he heard them on a disc provided by prosecutors. It was contained in discovery materials that prosecutors are required to turn over before trial.
Prosecutors planned to use some of the phone conversations Crouse had with friends and associates during the case, McMahon said.
"So imagine my surprise," he said. "I'm listening to the phone calls and up comes one with my voice, talking one-on-one with my client about trial strategy."
McMahon has asked a judge to have the prosecutor removed from the case.
The Sheriff's Department started using the recording system in 2003. A database of 5,000 phone numbers of local attorneys was entered into the system so that, if an inmate called one, the call would not be recorded. But the list was far from complete.
"We thought we had a better database," Toyen said. District Attorney Bonnie Dumanis said she was unaware of any instance in which a prosecutor or a district attorney's investigator listened to any protected conversations between lawyers and clients.