The sign a bystander saw the 13-year-old girl holding before calling police. Photo courtesy of the U.S. Attorney's Office.

A Texas man admitted Friday to kidnapping a 13-year-old girl at gunpoint and sexually assaulting her multiple times before he was arrested in Long Beach, according to federal authorities.

Steven Robert Sablan, 62, pleaded guilty to one count of kidnapping and will face a mandatory minimum sentence of 20 years in federal prison and a statutory max sentence of life in prison for the crime, according to authorities. He’s been jailed ever since his arrest in July.

Federal prosecutors said that Sablan admitted to abducting the 13-year-old girl on July 6 and using a gun to hold her against her will for several days. During this time, federal prosecutors said, Sablan and the girl traveled through state lines until they ended up in Long Beach.

There, according to authorities, a bystander saw the girl inside Sablan’s car holding a “Help Me” sign.

The gun police say Steven Robert Sablan used when kidnapping a 13-year-old girl last year in Texas. Photo courtesy of the U.S. Attorney’s office.

When officers arrived, they saw Sablan standing outside the vehicle and the girl, “visibly emotional and distressed,” mouthing the word “help” from inside the car, authorities said.

The officers detained Sablan and searched his vehicle where they found a black BB gun, a “help me” sign, and a pair of handcuffs, authorities said.

Authorities previously said that the girl had run away from home and her family had reported her missing before Sablan kidnapped her. Sablan had no previous connection to the girl, federal prosecutors added.