Government agents accuse a 20-year-old man of threatening to kill a Federal Protective Service inspector in Portland after a row -- touched off by a confiscated bicycle -- in Terry Schrunk Plaza.

Mark O. Allison faces up to year in federal prison if convicted in Tuesday's incident, which occurred in one of three downtown parks overtaken in 2011 by

demonstrators.

The park, which sits between City Hall and the new Edith Green-Wendell Wyatt Federal Building, has served as a default gathering place for homeless people as city officials

on downtown sidewalks.

About 1 p.m. Tuesday, a pair of Federal Protective Services inspectors, who serve as police on U.S. government property, spotted a bicycle chained to a tree in the plaza and tried to find its owner. When the owner could not be found, inspectors got a bolt cutter and began to remove the bike.

Suddenly they found themselves confronted by angry campers, who began shouting at them, according to a government affidavit.

A sign sits on the sidewalk outside Terry Schrunk Plaza, where campers squared off with federal officers on Tuesday.

One woman broke and ran from an inspector, who was preparing to detain her, and he drew his Taser. Another inspector handcuffed her.

"This furthered the mobs (sic) rage and they began to close in on us," one inspector recounted in the affidavit.

A man began trying to chest bump an inspector.

"You want to Tase me, too?" he yelled.

The man, identified in court papers as Angel T. Lopez, continued to try to chest bump the inspector, who grabbed the back of Lopez's head and pulled him to the ground. Lopez was later cited for failing to comply with a lawful direction.

As Lopez was taken to a patrol car, Allison pointed at Inspector Douglas Rommes, according to the affidavit.

"I'll (expletive) kill you," the court papers quote Allison as saying. "When you get off duty, you're mine!"

Mark O. Allison

Rommes arrested Allison, and the campers became enraged. The federal officers called Portland police for emergency backup, finding what they described as a "mob" standing in front of their vehicles and preventing them from moving.

Later that day, two federal agents interviewed Allison in the Federal Protective Service lockup. Allison's account of the incident disputed Romme's. He said he saw Rommes push his "street brother" -- Lopez -- and that he neither threatened nor yelled at the federal officer.

Allison recalled saying, "I still want to see you off duty," which he intended to convey that he wanted to speak to Rommes under normal circumstances, according to the affidavit. The document also noted that guns and uniforms provoke Allison.

"They cause aggression in me," he was quoted as saying. "I don't like guns. As soon as you take off that uniform and gun, I calm down. The mob was angry and it fed my emotions. Uniforms always screw me over."

Government prosecutors charged Allison with assaulting, resisting, or impeding certain officers or employees, which carries a potential one-year prison term. Allison was released from jail Wednesday.

-- Bryan Denson