By OLGA R. RODRIGUEZ

SAN FRANCISCO (AP) — Authorities are trying to determine if anyone helped two inmates who escaped from a California jail, traveled hundreds of miles and crossed into Mexico before being captured trying to walk back into the United States.

Jonathan Salazar, 20, and Santos Fonseca, 21, were arrested by U.S. Customs and Border Protection officials at a port of entry in San Ysidro — the nation’s largest border crossing — early Wednesday, Monterey County Sheriff’s Office Capt. John Thornburg said.

Thornburg said the two are in the custody of Monterey County officials and have been returned to a jail in Salinas, a farming city of about 160,000 people roughly 100 miles (160 kilometers) south of San Francisco.

Salazar and Fonseca escaped Sunday from the lockup in Salinas after climbing through a hole they made in the ceiling of a bathroom, squeezing through a hollow wall and kicking open a hatch. Officials found their jail-issued jumpsuits outside the building. Inmates often wear their own clothes under the jumpsuits, Thornburg said.

Investigators have not yet determined how long they worked on making the hole or if anyone else helped them escape or helped them after they were out. They were reported missing at 8:15 a.m. Sunday.

Thornburg said authorities received a tip that the pair, both born and raised in Salinas, had been spotted in the Mexican border city of Tijuana, around 400 miles (644 kilometers) south of Monterey County, and alerted federal officials.

CBP spokeswoman Jackie Wasiluk said the men didn’t present any documents. They said they were U.S. citizens, and a check of law enforcement databases told border inspectors that they were wanted by authorities.

How the pair made it to Mexico, why they decided to travel together since they allegedly belong to rival gangs and why they returned to the United States is under investigation, Thornburg said.

“The good news here is they are in custody again,” Thornburg said.

Salazar and Fonseca will be housed separately in a different housing unit from the one they escaped, Thornburg said, adding that officials had already made security improvements to the jail. He said he couldn’t provide details.

Before being spotted in Tijuana, investigators received a credible tip from an employee at a motel in Marina about 10 miles (16 kilometers) from the jail who told authorities Salazar had checked in there Tuesday morning, but authorities found no one in the room after a nearly eight-hour standoff, Thornburg said.

“It all looked like we had Mr. Salazar in a motel,” he said. “Unfortunately, last night he wasn’t there.”

Both had been in custody since 2018 and were awaiting trial on murder counts and “numerous other felony charges” in separate cases.

Salazar was arrested in the shooting death of 20-year-old Jaime Martinez as the victim drove in Salinas with his girlfriend and 18-month-old son. The woman was shot and treated at a hospital, while the child wasn’t hurt.

Police investigated the Oct. 12, 2017, shooting as gang-related. Officers said his tattoos, including the letter P on his cheek, refer to his Sureño offshoot gang, La Posada Trece, the Californian reported. His trial was scheduled to begin in January.

Fonseca told police after his arrest on homicide charges that his gang leader told him to kill someone to prove he was still loyal to the Boronda Boys, a subset of the Norteño gang, Detective Gabriela Contreras testified.

Fonseca is charged with shooting Lorenzo Gomez Acosta, 37, to death on June 2, 2018, while the victim sat in his car on a video call with his wife in Mexico, the Californian reported.

She saw a scuffle, heard her husband screaming “no” and then gunshots rang out, Salinas police Officer Froylan Aranda said. Acosta was reportedly chosen at random.

Three days later, Fonseca shot and killed Ernesto Garcia Cruz, 27, in a Salinas park, authorities said. He told police that the gang leader also ordered the slaying and that he picked his girlfriend’s ex-boyfriend “to send him a message,” Contreras said.