A prosecutor said Tuesday that Scott Peterson's (searchtelephone was tapped earlier this year and investigators may have listened in on interviews with journalists in case he admitted killing his pregnant wife.

"It's an investigative tool," said John Goold (search), a prosecutor in Stanislaus County. "They're seeking anything that might come out of that conversation, up to and including a confession."

Peterson, 30, has pleaded innocent to murdering his wife, Laci (search), and unborn son. Prosecutors have said they will seek the death penalty if he is convicted.

County prosecutors have sent about a dozen letters to journalists, a lawyer and a member of the public notifying them of the court-ordered phone taps, Goold said. The letter said only that the taps were authorized from Jan. 10 to Feb. 4, but Goold confirmed they were on Peterson's phone.

Goold also said investigators intercepted calls from one of Peterson's lawyers. Those calls are privileged conversations between attorney and client, and prosecutors say investigators do not listen in once the identity of the caller is determined.

Defense lawyers for Peterson did not return phone calls Tuesday.

The Modesto Bee newspaper and NBC were notified that calls from their reporters had been intercepted, Goold said.

Mark Vasche, executive editor at the Bee, said he was distressed that investigators had been able to eavesdrop on his reporters' conversations and said the newspaper would seek to listen to the tapes of their phone calls to Peterson.

"It's a little unsettling knowing that your conversations were being recorded and listened to," he said. "It just goes to the integrity of a free press and protection of sources and all those things."

Goold said he received a call from one citizen and several journalists concerned prosecutors were tapping their phones.

"They're all worried we're tapping reporters' phones. We're not," he said.