RALEIGH — North Carolina's prosecutors need the power to convene investigative grand juries in public corruption and financial fraud cases, the state's top law enforcement said at a news conference Thursday.

N.C. Attorney General Roy Cooper said he would ask legislators to allow grand juries in those cases and also ask that they make it a felony to lie to an agent from the State Bureau of Investigation.

"These cases aren't easy, and they aren't fun," Cooper said. "But they must be investigated thoroughly and independently."

Cooper and Wake County District Attorney Colon Willoughby, who also spoke at the news conference, said state public corruption cases get pushed to federal investigators, who have the power to call investigative grand juries in those cases. It's also illegal to lie to an agent from the Federal Bureau of Investigation, but not the SBI.

Prosecutors have been able to call investigative grand juries in drug cases for decades, Willoughby said.

"Twenty years ago, our Legislature said this tool was appropriate for people that are selling drugs," Willoughby said. "Why can't we use that tool for people that are selling our government?"

The chairman of the House Judiciary Committee, Republican Rep. Leo Daughtry, sounded dubious when he heard of Cooper's idea for investigative grand juries, saying if a bill is proposed, the committee will consider it.

The concern when Cooper proposed the grand juries several years ago was the prosecutors would "find a political enemy and start investigating them without as much evidence as you would normally use," Daughtry said. "People will have some discomfort ... Certainly, we'll be willing to talk about it."

Making it a felony to lie to an SBI agent may have some merit, he said.

Cooper didn't mention specific cases but said the SBI has investigated many public corruption cases, including the campaigns of two governors, governors' staffers, the state Highway Patrol and the Department of Correction, as well people in the legislative and judicial branches of government.

In November 2010, former Gov. Mike Easley accepted criminal responsibility in state court for an improperly filed campaign finance report at the same time as the feds ended their investigation. In August 2010, the State Board of Elections fined the campaign committee of then-Gov. Beverly Perdue $30,000 for failing to report more than 40 flights — many by wealthy donors — during her 2008 campaign.

If they approved Cooper's proposal, legislators would essentially be saying OK to expanding prosecutors' powers to investigate themselves. When asked why they would do that, Cooper said: "I believe that public officials, most of them, want to get the bad ones out. And making sure that investigators and prosecutors have the right tools to do that is important. We hear lots of elected officials talk about clean, open government free from corruption. We've got to make sure we have the tools to investigate and prosecute the wrongdoers."