LOS ANGELES (Reuters) - The sheriff of the California county that operates the jail from which three prisoners escaped earlier this month said she was “deeply concerned” about how long it took to discover the men were missing.

Inmates Jonathan Tieu, 20, Hossein Nayeri, 37, and Bac Duong, 43, (L to R) are seen in an undated combination photo released by the Orange County, California, Sheriff's Department. REUTERS/Orange County Sheriff's Department/Handout via Reuters

Hours after the last two fugitives were captured, Orange County Sheriff Sandra Hutchens said she had ordered an investigation into how the trio broke out of a maximum-security jail in Santa Ana and went unnoticed for about 16 hours, according to a letter her office released late on Saturday.

“I have been very clear from the onset of the jail escape investigation that I am deeply concerned about the length of time it took to recognize that three maximum security inmates were unaccounted for,” Hutchens wrote in response to a letter she had received from the Association of Orange County Deputy Sheriffs about the escapes.

“I have initiated an internal administrative investigation to determine the facts of what occurred, contributing factors to the escape and inmate count procedures,” Hutchens continued in the letter, which she later disclosed in an emailed statement.

The last two men who escaped on Jan. 22 were arrested on a tip from a man who saw their stolen van in the parking lot of a San Francisco Whole Foods supermarket, authorities said on Saturday, the day after a third escapee turned himself in.

Hutchens said the department had taken immediate action to ensure no repeat of the incident. But she said it had not made any personnel changes as of yet because of the escapes.

Hossein Nayeri, 37; Jonathan Tieu, 20; and Bac Duong, 43, made their getaway by cutting through steel grating inside the jail, climbing through a plumbing conduit to the roof and lowering themselves four floors to the ground with bedsheets, authorities said.

The search for the escapees came to an end when Nayeri and Tieu were apprehended in San Francisco’s park district about 375 miles (604 km) north of the lockup.

The third escapee, Bac Duong, 43, gave himself up on Friday in Santa Ana, officials said.

Nayeri, the presumed mastermind of the breakout, was in the Orange County jail on charges stemming from the 2012 mutilation torture of a kidnapping victim.

Tieu was facing murder charges, and Duong has been charged with attempted murder and assault with a deadly weapon, among other crimes. The pair is reputed to be connected with Vietnamese-American street gangs.

Nooshafarin Ravaghi, a writer who taught English at the Orange County jail, is accused of furnishing the inmates with Google Maps information that included overviews of the jail rooftop and surrounding areas.

Ravaghi, who was arrested on Thursday, is expected to be arraigned on Monday.