SANTA ANA, Calif. » One of three inmates who escaped from an Orange County jail was ordered deported to Vietnam in 1998 but remained in the country and racked up a lengthy rap sheet, immigration officials said today.

Bac Duong, 43, came to the United States legally in 1991 but was ordered removed seven years later, Immigration and Customs Enforcement said in a statement. The statement did not say why.

Duong checked in with federal immigration officials as required until August 2014, the statement said.

U.S. officials can’t detain immigrants indefinitely while they await deportation and must release most after six months. Under a 2008 agreement, Vietnam will provide travel documents to help repatriate immigrants but only those who entered the U.S. after July 1995.

Duong and two other inmates escaped from an Orange County jail Friday by sawing through a quarter-inch thick grill on a dormitory wall and climbing through plumbing tunnels to reach an unguarded area of the roof, where they moved aside razor wire and rappelled to the ground using a bed linen.

Duong and Jonathan Tieu, 20, and Hossein Nayeri, 37, are considered dangerous, and all were awaiting trial for separate violent felonies. They have now each been charged with the escape.

Sheriff’s officials are focusing the search on neighborhoods where the men could be hiding, especially among Orange County’s sizable Vietnamese-American population, which is among the largest in the U.S.

Two of the men have ties to local Vietnamese gangs, sheriff’s Lt. Dave Sawyer said.

Tieu had been held at the jail since 2013, accused of murder and attempted murder. Duong faced attempted murder and assault charges in the shooting of a man in November.

Nayeri was arrested in 2014 on charges including kidnapping and torture. Authorities said he abducted a marijuana dealer, burned him with a blow torch and cut off his penis because Nayeri thought the man had buried money in the desert.

The men were gone for as long as 16 hours before officials noticed they were missing from the common dorm they share with more than 60 other inmates at Orange County Central Jail. An attack on a guard delayed a Friday night head count by hours.

The sheriff’s department has been slow to add more rooftop security cameras at the jail despite a grand jury’s recommendations for eight years straight, according to a report in the Orange County Register. The department has said since 2008 that budget constraints prevented upgrades to the camera systems at the five county jails.

The escape was eerily similar to one last year in New York, where two inmates cut through a portion of a wall hidden under a bunk bed and used piping and tunnels inside the facility to get out. But the search for the pair focused on nearby woods instead of a dense urban population.

A major question for California investigators will be how the men could plan and execute their escape with such precision, said Kevin Tamez, a managing partner for MPM Group, a Philadelphia-based firm that consults on prison security, management and infrastructure.

It’s likely someone slipped them blueprints or told them how the bowels of the jail were laid out, he said.

There is no evidence so far that the trio had help from the inside, but authorities know it’s a possibility, Orange County sheriff’s Lt. Jeff Hallock said.

It was the first escape in nearly three decades from the California facility built in 1968. It holds 900 men and is in Santa Ana, about 30 miles southeast of Los Angeles.

Hallock said the jail’s general policy is to do walk-throughs every hour to check on inmates. More thorough searches are done randomly, he said, declining to give more details.

It’s unclear why the inmates charged with violent felonies were housed in the common dorm with dozens of others. Assigning them to a large, busy room likely made it easier for them to avoid detection, said Martin Horn, a professor of corrections at John Jay College of Criminal Justice at City University of New York.

Federal authorities are offering $50,000 for information leading to their capture.

Associated Press writer Christopher Weber contributed to this report.