The sixth protester, the one who wasn't arrested, was a man who called himself "Chris Taylor." He was in fact an undercover officer planted by the Arapahoe County Sheriff's Office.

Taylor, whose real name is Darren Christensen, attended a training session in nonviolence with the other protesters the day before the sit-in, as well as the protest itself at Allard's Arapahoe County office.

The protesters who were taken in by Christensen say they are angry at the deceit and at being monitored covertly.

"That's a really scary thing," said Bonnie McCormick, a retired art teacher from Boulder who was arrested when she refused to leave Allard's office.

"That's outrageous to me," said Sara Jane Geraldi of Boulder, 32, a mother and part-time social worker, who also was arrested.

The protest at Allard's office was one of two incidents in which local police are known to have placed undercover agents in protest groups during the heavy- combat phase in Iraq last spring.

In the other incident, two Aurora officers infiltrated a group that staged a sit-in outside Buckley Air National Guard Base on March 15. Nineteen people were arrested in that protest, but only 18 were charged.

Testimony in the legal proceedings following the two protests provides a rare glimpse at how law enforcement agencies spy on protest groups.

In the Allard case, the sometimes contradictory testimony by sheriff's deputies points to police informants within the peace movement. That case is still entangled in a dispute over what information the sheriff's office must disclose to defense attorneys.

The American Civil Liberties Union charged last month that information gathered by local law enforcement agencies is ending up in FBI files. The FBI, however, denies it collects data on peaceful political groups.

Local protest leaders say surveillance was particularly unnecessary at the demonstrations last spring because police were told everything in advance - where protesters would march, how many people would commit civil disobedience, even where they would park their cars.

"It's not like some secret, clandestine organization that's out to overthrow the government," said Carolyn Bninski of the Rocky Mountain Peace and Justice Center in Boulder, who helped organize the Buckley protest. Furthermore, the protesters pledged to remain nonviolent, Bninski said.

But Sgt. Tim O'Brien of the Aurora Police Department's intelligence unit, said he had no way of knowing if the demonstrators were telling the truth.

"We wanted to make sure that their real plans weren't to suddenly stage a riot and start throwing bricks and bottles and stuff like that," O'Brien said, and points to demonstrations in other parts of the country that did get out of control.

"Who's to say that a member of a very violent faction joins this organization and starts to preach violent protest and-or turns it into a violent protest while it's going on - that we don't know," O'Brien said.

Arapahoe County Sheriff Grayson Robinson said the department had tips that a group of protesters was planning to block traffic. Officers were trying to find out if it was the same group that planned to protest at Allard's office.

"We were trying to develop information to ensure that if, in fact, that was a plan, that we were prepared to assist the motoring community with their travels," Robinson said.

He said the tip about blocking traffic did not come from undercover agents.

Both police agencies say the instances of covert surveillance that have come to light are the only ones in which they secretly observed a political group since the Sept. 11 attacks. Neither agency keeps files on protesters, the officials said.

The Denver Police Department in May agreed under pressure from the ACLU to stop maintaining files on political groups that are not engaged in criminal activities. Denver police political files went back at least 25 years.

But the ACLU and the Denver police are still at odds over whether officers may perform political surveillance while on special assignment with the FBI's Joint Terrorism Task Force. The ACLU sued in October to obtain the contract between Denver and the FBI.

Aurora and Arapahoe County are also members of the task force.

O'Brien. of the Aurora police, would not detail his agency's involvement with the task force.

Sheriff Robinson said one deputy is assigned to the task force, but added that the task force doesn't infiltrate protest groups.

Most of the area's law enforcement agencies trade information as part of the Multi-Agency Group Intelligence Conference, or MAGIC.

The possibility that people will end up in a police dossier - or a national FBI data base - could have a chilling effect, Colorado ACLU legal director Mark Silverstein said.

"It's not the certainty that there's an agent that causes people to silence themselves," Silverstein said. "It's the fear."

Special Agent Ann Atanasio of the FBI's Denver office said the agency does not keep files on people in ordinary political groups.

"The FBI is not going to keep a file on them. If they're not doing something illegal, we have no authorization to monitor behavior that is not a threat in some way," Atanasio said.

The agency's activities are focused on people who might commit acts of terrorism, Atanasio said.

Testimony in the case arising from the protest at Allard's office indicates that protest groups are on the radar screens of some law enforcement agencies on a continuing basis.

Christensen, the Arapahoe County officer who posed as "Chris Taylor," testified that he didn't recall whether he heard about the demonstration at Allard's office from his supervisor or from an informant.

"Did you regularly have individuals that informed you about upcoming protests?" asked Martin Stuart, Geraldi's lawyer.

"Yes," Christensen responded.

Maintaining contact with informants was part of his job, said Christensen, who has since gone to work for the Elbert County sheriff.

Christensen and a female officer, Liesl McArthur, infiltrated a group of about 30 demonstrators. They showed up at a Denver church where protesters received training in nonviolence and were advised by an attorney the day before the sit-in.

Christensen testified that he went because of the possibility that the protesters might be a threat to Allard's staff. That view didn't change even after he learned that two of the people who planned to commit civil disobedience were over 70 years old.

"Any protest, anything such as this, there is always a security risk," he said.

"Did you have any concern about weapons with these individuals?" Stuart asked.

"Always . . . I always have concerns with weapons," Christensen said.

"So it didn't matter who they were, anybody who decided to go to Senator Allard's office to protest, you'd have a weapon concern?" Stuart asked.

"Yes," Christensen said.

Christensen cited those concerns as the reason he continued to pose as one of the protesters right through the time they were arrested.

But Christensen's supervisor, Sgt. Al Holstein, had an additional goal. Holstein testified that he wanted Christensen to build up rapport that could be useful in monitoring the group in the future.

"Yeah, in case, down the road we would do that again, and he could go to other protests, organizational meetings, or whatever, just to gather intelligence in the future," Holstein said.

Less is known about the Aurora cases, which were resolved more quickly. One juvenile received deferred prosecution, 13 people were convicted on misdemeanor charges, and four were acquitted.

Jury disapproval of the undercover tactic may have been a factor in the acquittals, speculates Kevin McGreevy, the pro bono attorney for one of the defendants who was convicted.

Two officers, Chris Hurley and Brad Wanchisen, attended the planning meeting, posing as a couple.

Neither testified at the trials. But O'Brien testified the agents were planted because the demonstrators had announced they were going to commit a crime, namely the acts of civil disobedience.

Protesters in both demonstrations were drawn from a half-dozen small groups that disagree with American policy on a wide array of subjects. In addition to opposing the war, some protesters were critical of U.S. support for Israel, while the group at Allard's office presented a resolution calling for creation of a Cabinet-level "department of peace."

They feel betrayed by the undercover agents, who pretended to be sympathetic to them.

"We felt very violated," said Nancy Peters, who was arrested at the Buckley demonstration. Her $250 fine was waived, but she was assessed $107 in court costs and ordered to perform 16 hours of community service.

Geraldi, the parent who was arrested at the Allard demonstration, said the man who presented himself as "Chris Taylor" ingratiated himself by talking about his children.

"He used my motherhood and my family experience against me. He used that as a hook," Geraldi said.

Geraldi was hurt to learn - through the court testimony - that Christensen's real thoughts about the protesters was that they were "weird."

"(His) thinking that (we're weird) is enough reason for a department to send people undercover?" she asked in a tone of incredulity.

Geraldi said Christensen might have thought she's weird because she has several tatoos on her arms. They picture flowers and fairies.

"It's not like I've got swastikas and barbed wire," she said.

Perhaps most unsettling to Geraldi was Christensen's testimony that much of his undercover work for the Arapahoe County sheriff involved being solicited on line for deviant sex.

"We're lumped in with pedophiles . . . it was like, whoa," she said.

Geraldi said she participated in the protest because calling and writing letters to her senator seemed ineffective. But she'll hesitate to participate again because being part of a police file might hurt her children.

McCormick, the retired teacher, said, "This is as bad as the war - it's intimidating."

"What happens is, people will be afraid to do what I've done, this old lady," McCormick said.

She, however, "won't be deterred."

"If you're afraid to say how you feel, you've lost your free speech," said McCormick, who has been arrested several times at demonstrations in recent decades.

She also said the police didn't need monitors at a group committed to nonviolence.

morsonb@RockyMountain News.com or 303-892-5072