The U.S. Marine being held in a Mexican prison opened up to Fox News’ Greta Van Susteren Friday, telling the story of a failed escape attempt that nearly cost him his life.

In late March, Marine Corps Sgt. Andrew Tahmooressi said he made a wrong turn and wound up in Mexico — and under arrest for the guns in his car.

This May 3, 2014, photo shows Sgt. Andrew Tahmooressi left, who is being held at Tijuana’s La Mesa Penitentiary. The 25-year-old Marine Corps combat veteran is being held on weapons charges for mistakenly crossing the border with a shotgun, handgun and rifle in his vehicle. (AP Photo/U-T San Diego, Alejandro Tamayo)

He’s facing up to 21 years in Mexican prison for having his legally registered AR-15 rifle, .45-caliber pistol and 12-gauge pump shotgun in his car.

Though a prior lawyer of his advised him to “stick to the script” and not say too much, Tahmooressi has been vocal throughout his ordeal, and on Friday he revealed the near-success of his escape attempt to Fox News.

He was making a phone call, he told Greta Van Susteren, when he saw a 9-foot cage — and an opening.

“I ran and I grabbed a hold of the top of the cage and I got myself on top of the cage,” Tahmooressi said.

He ran across multiple rooftops, scrambling over fences and under barbed wire.

“I managed to get to one of the front gates of the prison and I couldn’t find any way out,” Tahmooressi said. Then, he said, he saw a pipe he could you to shimmy out of, but by then it was too late: a guard had spotted him.

“[The guard] shot at me,” Tahmooressi said, “and I saw the impact a little bit above my head and to the right, maybe 4 feet away.”

“That’s when I got on the ground with my belly to the ground and my hands behind my head and I gave up,” he said.

Hear the full interview here.

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