Orange County Sheriff's Lt. Jeff Hallock announced the arrest and also said the three inmates who broke out of the jail in Santa Ana last Friday might be living in a van stolen Saturday in Los Angeles.
Nooshafarin Ravaghi, an ESL teacher from Rancho Santiago Community College who had worked at the jail for six months, was arrested Thursday, Hallock said.
She is scheduled to make an initial appearance in court on Friday, according to online inmate records. The listing didn't specify potential charges against Ravaghi.
One of the escapees, Hossein Nayeri, attended several of Ravaghi's classes at the Central Men's Jail.
Officials said they believe Ravaghi, 44, provided material to Nayeri, including maps and overhead photos of the area around the jail. Authorities have said they believe Nayeri was the ringleader in the escape.
Investigators are looking into whether Ravaghi brought tools to the jail for Nayeri to aid in his escape. Hallock said she has denied that allegation.
But he said Nayeri and Ravaghi likely had more than a teacher-student relationship.
Ravaghi was a part-time instructor in the inmate education program, said Judy Iannaccone, a spokeswoman for the Rancho Santiago Community College District. Ravaghi began working in the program in fall 2014 and passed a background check before her assignment.
At least nine other people connected to the three escapees have been arrested in the past two days.
Authorities feel very strongly that Nayeri, 37; Jonathan Tieu, 20; and Bac Tien Duong, 43, are still together.
Charges against the fugitives include murder, attempted murder and torture.
Duong is the suspect in the theft of a white GMC van that was stolen on Sunday, Hallock said.
Orange County Sheriff Sandra Hutchens said Wednesday that investigators are sure the trio had outside help.
The sheriff said she doesn't believe anyone sneaked into the jail.
Investigators are trying to determine what tools were used in the escape. The sheriff said some of the security bars that were bypassed during the escape showed clean cuts and were too thick to have been sawed by prison-made implements.
Hutchens said authorities are embarrassed.
"There's not a member of the sheriff's department ... that does not feel that we let the public down," she said.
The fugitives likely escaped after a 5 a.m. headcount but it wasn't until more than 15 hours later that authorities discovered the escape.
That has prompted a change in other counts administered during the day, when some inmates have gone to court, the doctor or other parts of the jail. Now jail officers have to call and confirm the inmate is where paperwork indicates he should be.
Authorities are offering a $200,000 reward for information leading to the fugitives' capture.