SAN FRANCISCO -- NBC has learned that before Scott Peterson was named as a suspect, investigators tapped his phone and even recorded his conversations with reporters.

NBC reports legal experts are shocked to learn of the extraordinary tactics used by investigators in the Scott Peterson case. They say wiretaps in a local murder case are almost unheard of. The recording of conversations with the media is even more unusual, they say.

The Stanislaus County District Attorney's Office confirms investigators tapped Scott Peterson's phone conversations a little more than two weeks after the disappearance of his pregnant wife, Laci Peterson.

NBC's Jodi Hernandez in San Francisco received notice by certified mail Friday that her conversations with Peterson were among those recorded between Jan. 10 and Feb. 4.

During that time, Hernandez made nearly 50 phone calls to Peterson's cell phone to arrange her on-camera interview.

Legal experts say the wiretaps are troubling.

"What we're talking about here is a most extraordinary event, and it's one that, as a civil libertarian, is very worrisome," said Bernard Segal, a Golden Gate University law professor.

Segal says getting a wiretap isn't easy for a local prosecutor.

"The investigators had to set out in detail the facts which support the belief that Scott Peterson had knowledge of the death of his wife and child. And that his conversations were a likely source of information indicating guilt or involvement in those crimes," he said.

That means investigators suspected Peterson just two weeks after Laci disappeared, but at the time, they weren't admitting it, Crouch said.

During the initial stages of the investigation, Detective Doug Ridenour had been quoted as saying that Scott Peterson has "not been eliminated from the investigation ... nor has he been identified as a suspect."

This duplicity could later raise questions in a juror's mind about the tactics used in this case.

"If they made a misleading statement here ... did they make any misleading statements or unintentional inaccurate statements in the request for a warrant?" Segal said.

Investigators began recording Peterson's phone conversations the day after divers reported finding something in the Berkley Marina.

"I suspect, to be perfectly frank with you, the reporter's conversations were the ones they wanted all along ...," Segal said.

"That might be information that never made itself into a news story and therefore, was sealed in the reporter's notes and in the reporter's files. And the DA would have a very tough time trying to subpoena that or obtain a search warrant."

Legal experts say the wiretaps will be the subject of a major court battle -- one that could help Scott Peterson build a defense based on questionable police practices.

"Each side will fight it to the legal death, if you will," Segal said. "My prediction is a year's delay is going to be added to this case."