A law passed by the legislature last year that took effect in March requires every police agency to record or videotape interviews that officers make with a homicide suspect.

The legal requirement puts North Carolina ahead of many states in ensuring that confessions are preserved, experts say.

"It's a relatively new phenomenon," said Richard Dieter, executive director of the Death Penalty Information Center in Washington. "It has been slow in coming."

Most agencies in the Triangle have equipment set up to comply with the law -- from an audio recorder in Hillsborough to a $22,244 system that Raleigh Police Department installed.

But Pittsboro Police Chief David Collins said his department is struggling to find the money to meet the requirements.

"It's a mess," he said. "It's going to be a challenge to get everything in place, but we will."

Technology to record interviews has been around for decades, but the use of taping in interviews has been a slower process.

Dieter said taping can prevent false confessions, which the New York-based Innocence Project estimates happened in a quarter of the cases in which DNA has since freed prisoners.

"It's strange, but people confess to things they didn't do," Dieter said. "There's often a reason -- they were pressured or interrogated for 36 hours without food."

James Coleman Jr., a Duke University law professor, said taping interviews also will help bolster the reputation of police once jurors can see that legitimate confessions were done legally.

"It gives assurances to everybody that the system is working properly," Coleman said.

Capt. Chuck Hurst of the Raleigh Police Department said Raleigh detectives have already used the taping system several times. In the department's white cinder-block interview room in its downtown headquarters, the only sign of a video camera is a dark-gray ball on the ceiling, similar to security cameras installed in retail stores.

The law allows suspects to ask that they not be taped, but there's no legal requirement for police officers to inform suspects about the taping, Hurst said.

The system is easy to use -- a necessity for police officers, Hurst added.

"Cops can be hard on things, but it's held up," he said.

Carrboro Police Capt. J.G. Booker said his department will pay about $14,000 to upgrade its surveillance system and to install a video-recording system in its interrogation room.

"It's an expensive venture for any agency," Booker said. "When you're under the gun at 2 or 3 o'clock in the morning on that major case, you want something that's user-friendly."

Neither Knightdale nor Wendell police departments has a recording system, but their police chiefs say that their low crime levels make it unlikely they'll ever need to interview a homicide suspect.

"We've never had a homicide," Knightdale Police Chief Richard Pope said.

Wake Forest is upgrading it system to the tune of $20,000, said Lt. Trent Coleman. Officers plan to use it for any violent crimes.

Coleman said he prefers the system.

"I can concentrate on the actual interview instead of writing stuff down," he said. "If it does go to court, you can say 'here it is.' "

(Staff writer Jesse James DeConto contributed to this report.)