One of two men charged with imprisoning a 15-year-old girl in a metal box at their Northern California marijuana farm was sentenced Wednesday to 31 years in federal prison.

The girl, who had run away from home in Los Angeles, was sexually abused by both men and required to help prepare the illicit pot for sale before she was rescued in 2013, authorities said.

Ryan Patrick Balletto, 36, pleaded guilty to marijuana trafficking, firearms possession and using a minor to violate drug laws.

The charges carry a maximum penalty of life in prison, but Senior U.S. District Judge Charles Breyer of San Francisco sentenced him to 31 years. Prosecutors had argued for a 32-year sentence, while a plea agreement called for a minimum of 27 years.

“The circumstances of this offense are among the most horrific of any case prosecuted in this District in recent memory,” prosecutors wrote in seeking the higher sentence. They included “the sadistic physical, sexual, and psychological abuse of a fifteen year-old girl over a prolonged period of time.”

Balletto’s attorney, James Scott Thomson, did not immediately respond to telephone and emailed messages Wednesday.

The second man, Patrick Pearmain, 31, was sentenced in April to 12½ years in prison on similar charges after authorities said he also imprisoned the girl in a metal tool chest four feet long, two feet high and two feet wide.

Lake County sheriff’s deputies and federal Homeland Security investigators said they found 1,300 marijuana plants and numerous firearms, including assault-style rifles with night vision scopes, on a remote property owned by Balletto about 100 miles northwest of Sacramento. They also found body armor, large quantities of ammunition and a gas mask.

Prosecutors said Balletto met the runaway girl during a trip to Los Angeles in 2013 and told her she could come live with him, his wife and children. Instead, they said he took her to the marijuana farm and put her to work trimming marijuana buds for about three weeks.

Aside from the sexual abuse, he admitted in the plea agreement to shocking her with a cattle prod, chaining her to a couch or bed by her neck, and forcing her into the tool chest.

Authorities said they found the tool chest cut with air holes, with a blanket inside, decorated inside with a decal of a human skull and the words “Bone Collector.” The girl told authorities she was kept in the box on two occasions for a total of three days. Balletto said he kept a chain around her neck for three or four days.

“Balletto told her she was a ‘trooper’ because she didn’t scream inside the box,” investigators said in court documents describing the girl’s account of her imprisonment.

She told them the men stuck a hose through one of the air holes to wash her off and wash away human waste.

She received “several months” of residential mental health treatment in another state after she was rescued, authorities said.