A man accused of setting fire to a Portland jail and subsequently identified by a back tattoo of his last name pleaded guilty Wednesday to a federal arson charge.

Edward Thomas Schinzing, 32, faces a minimum of five years in prison for the May 29 fire set to the Multnomah County Justice Center in downtown Portland. He told a judge he knew people were being held in custody -- 289 inmates -- on the upper floors of the building, The Oregonian reported.

Prosecutors believe Thomas Schinzing spread a May 29 fire in the Corrections Records Office of Portland's Justice Center by moving flaming papers into separate cubicles. On Wednesday he pleaded guilty to a federal arson charge.

Prosecutors believe Thomas Schinzing spread a May 29 fire in the Corrections Records Office of Portland's Justice Center by moving flaming papers into separate cubicles. On Wednesday he pleaded guilty to a federal arson charge. (Department of Justice)

Investigators said Schinzing was among several hundred people who gathered to protest nearby the Justice Center before walking over to the building. At one point, a group broke windows in the building and climbed inside some offices.

Three civilian employees were inside and fled the area. Around 30 people entered the building and damaged office equipment, including computers and furniture, prosecutors said.

Schinzing, who was shirtless, was identified by his name tattooed on his back. He left the building and later came back wearing a shirt and lit paper on fire and moved it to several cubicles, authorities said.

A sprinkler system extinguished fires after a few minutes.

Prosecutors believe Thomas Schinzing spread a May 29 fire in the Corrections Records Office of Portland's Justice Center by moving flaming papers into separate cubicles.

Prosecutors believe Thomas Schinzing spread a May 29 fire in the Corrections Records Office of Portland's Justice Center by moving flaming papers into separate cubicles. (Department of Justice)

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The vandalism prompted officials to erect a fence around the building, which became a target for demonstrators in the following weeks. Schinzing was on probation for a domestic violence charge at the time of the fire.

He has several misdemeanors and two prior felony convictions, the newspaper reported.