At least $500,000 worth of evidence was recovered, including 29 stolen cars and more than 100 grams of crystal methamphetamine or "ice," the major said. Also recovered were a .45-caliber pistol with 53 rounds of ammunition and a 20-gauge, double-barreled shotgun.

There were 4,079 motor-vehicle thefts from January to June 2004 on O'ahu, according to the state attorney general. In the same months in 2003, there were 5,018 motor-vehicle thefts reported.

A tip led Kalihi-based officers to people who were stealing cars — some old, some new — and selling them for a fraction of their cost.

Since February 2004, police officers and agents from the FBI and the Bureau of Alcohol Tobacco Firearms and Explosives have worked to break up the ring, said Ballard, who heads HPD's District 5 patrol area in Kalihi.

Officers began to infiltrate the group, and undercover officers began buying cars from the thieves, Ballard said. The buys took place in parking lots on Sand Island and in secluded locations near the docks in Honolulu Harbor, police said.

Other buys took place in Kalihi, Pearl City and Wai'anae.

In some instances, undercover officers were buying highly modified, $50,000 sport utility vehicles for as little as $3,500.

Of the 29 cars stolen and sold to undercover officers, seven F-150 Ford trucks, Ford Explorers and Ford Expeditions were swiped off container ships by employees working for a local car company. The employees, who were responsible for picking up cars at the dock and driving them to the lot, have been fired, police said.

Many of the older vehicles were stolen from owners' garages. Police said thieves drove around the island looking for cars to steal.

Two of the cars recovered had been carjacked, and seven of the 20 people arrested face felony robbery charges in connection with those carjackings.

All of the stolen cars have been returned to their owners except two which are being held as evidence in the carjacking cases.

Once undercover officers had earned the group's trust, offers to sell more cars poured in, police said.

"We could have made two buys a day for as long as we wanted," Ballard said. "We had to turn down some."

With a steady stream of cars moving, the thieves began offering drugs and guns to undercover officers.

Police responded by buying more than 100 grams of ice and two guns.

Of the 20 arrests, 11 individuals face federal prosecution and nine face state cases that have been forwarded to the city prosecutor's office. The 20 were arrested on a variety of felony theft, drug, and firearm charges, including promotion of a dangerous drug, possession of stolen property and robbery.

Evidence gathered led to the creation of 59 separate criminal cases, all of which remain open and under investigation, police said.

Police gathered that evidence for almost a year before making the 20 arrests over two days last month.

On Jan. 20, police arrested seven people they believe were the most violent of the group, based on previous convictions and their participation in an alleged carjacking.

Those arrests reduced the risk of a violent reaction from the remainder of the suspects once police started closing in, Ballard said. The next day, 13 more arrests were made at undisclosed locations across O'ahu.

Once officers in Kalihi had identified the ring's major players, officers from Pearl City (District 3), and Kapolei (District 8), and an investigator with HPD's violent-crime unit became involved.

Kalihi officers are among two crime-reduction units on O'ahu that regularly serve search warrants and make their own cases. The Kalihi unit is staffed by veteran undercover officers, and the unit's activities dictate the type of crime-reduction operations undertaken on O'ahu, police said.

There are eight such units on O'ahu, one in each district, that specialize in undercover work.

Ballard said the investigation was one of the largest stolen-vehicle cases that she has ever seen.