One of California’s 3,900 incarcerated firefighters died in the line of duty

California employs roughly 3,900 nonviolent offenders to put out wildfires, and one such inmate firefighter died Thursday in the line of duty.

Matthew Beck, 26, was leading a group attempting to contain a fire in the remote Hoopa Valley area of Northern California when a 120-foot tree uprooted and fell on him. He suffered fatal head, neck, and back injuries and died at the scene, according to California’s Department of Corrections and Rehabilitation.

Beck was convicted of burglary in 2014. He was serving a six-year prison sentence at one of California’s 43 fire camps. Beck was expected to be granted parole this October, reported Reuters.

The California Department of Corrections and Rehabilitation Conservation Camp program has been around since the 1940s. The dangerous, labor-intensive posting is made up entirely of volunteers, and inmates make up about 20 percent of California’s fire crews.

Beck was the fourth inmate firefighter killed in the history of the program. Others include a female inmate in Malibu last year after she was struck by a loose boulder and an inmate who suffered a fatal heart attack while on the job in 2007.

For their contributions, Department of Corrections removes two days from the prisoner’s sentence for every day in camp. They are also paid $1.45 per day in camp, plus an additional $1 an hour for time on the fire line.

The program has faced controversy. A 2014 BuzzFeed article explored whether the program borders on slave labor, claiming the cheap workforce saves the state over $1 billion a year. The Department of Corrections says the savings actually add up to about $100 million annually for taxpayers.

Inmate Robert Lang spoke to CBS about the program in October.

“I’m giving back to the community for what I did,” Lane said. “We’re not really convicts on the back of this bus; we’re treated as firefighters,” he said, adding, “It is a good feeling….it lets you know that you’re worth something.”