Maria Delia Aviles-Rodriquez, 36, of Paso Robles and King City was arrested at approximately 7:30 p.m. in connection with aiding and abetting kidnapping, child abuse, contributing to the delinquency of a minor and the destruction of evidence.
Search warrants were served on Aviles-Rodriquez' residence in Paso Robles as well as for her vehicle. Aviles-Rodriquez has been booked into Monterey County Jail.
The Monterey County Sheriff's Office is continuing to search for 16-year-old Eunice Serrato and her boyfriend Juan Manuel Salazar Jr., 19, with the assistance of the FBI, Interpol, as well as state, local and federal agencies.
An Amber Alert remains in effect for Serrato after Reyes and Fraga, were found dead inside Serrato's parents' home at 62240 Railroad Ave. at around 10 p.m. on July 28.
The sheriff's office later concluded Salazar Jr. who is a person of interest in the case, abducted Serrato.
The sheriff's office has also recovered an Acura Integra that they believe is related to the case.
Investigators believe Salazar Jr. is bound for Mexico with Serrato in a blue 2000 Chevy Tahoe with California license plate No. 6W54124.
Salazar Jr. has black hair and black eyes. He is around 5 feet 6 inches tall and weighs 170 pounds. He has glasses, could have a gunshot wound and is considered armed and dangerous, according to authorities.
Salazar Jr. may be traveling with a third person, 21-year-old Rogelio Aviles, who is now a person of interest as well, the sheriff's office said.
Serrato is described as about 5 feet 5 inches tall, weighs about 130 pounds and has brown hair and brown eyes, the sheriff's office said.
Deputies say she has a tattoo on her right middle finger that says "3/10/10," one that reads "Love," on her back and "Vellen" is tattooed on her upper right leg.
Serrato was wearing a blue and white shirt, pink jacket, blue jeans and sandals when she was last seen, the sheriff's office said.
Deputies also identified a tan 2007 Honda Civic as being associated with Aviles and the case. The California license plate number on that vehicle is 6JUK098.
On July 29, 39-year-old Juan Manuel Salazar Sr., the father of Salazar Jr., turned himself in to deputies at a King City sheriff's substation after being identified as a person of interest in the disappearance of Serrato from the scene of the double homicide.
Salazar Sr. is not in custody, according to the sheriff's office.
Anyone with information regarding the case should call Monterey County sheriff's Detective Brett Speirs at (831) 755-3805, the Tip Line at (888) 833-4847 or any local law enforcement agency.