JANESVILLE, Wis. — One night last week, dozens of chanting activists filed into the lobby of a hotel here, demanding that it cancel a Donald Trump town hall set for the following day. Within minutes, three members of Trump's advance security team were in the lobby, and things escalated quickly.

An official with the Trump advance security team, a 61-year-old former FBI agent named Don Albracht, began circling the room, putting his phone in the faces of protesters and filming them. As they chanted "build communities, not walls," Albracht ripped a sign out of one protester's hands, jutting his phone within inches of her face, as her comrades shouted objections.

When some of the protesters tried to return the favor by filming Albracht at close range, one of Albracht's associates pulled a protester away, screaming at her and wagging a finger in her face, an exchange captured in a video taken by activists with the group Stand Up For Racial Justice.

Neither the Trump campaign nor Albracht would comment on the protest or the role of private security personnel like Albracht on Trump's campaign. After a Trump speech on Wednesday in Appleton, Wisconsin, Albracht explained "our policy is that we're not going to comment, because you just never know whether you're going to get a fair shake."

The fracas in Janesville was only one example of the aggressive tactics Trump's security has been using to tamp down even peaceful protests. A POLITICO investigation revealed that Trump has assembled a privately funded security and intelligence force with a far wider reach than other campaigns' private security operations: tracking and rooting out protesters, patrolling campaign events and supplementing the Secret Service protection of the billionaire real estate showman during his nontraditional campaign for the GOP presidential nomination.

The investigation ? which utilized Federal Election Commission reports, state licensing records, court filings and interview accounts or testimony from more than a dozen people who've crossed paths with Trump's security ? found that the tactics of Trump's team at times inflamed the already high tensions around his divisive campaign, rather than defusing them.

The Trump campaign could be forced to publicly justify its security tactics in June when a New York state court is set to hear a little-noticed case brought by a handful of protesters who allege they were assaulted by five Trump security officials during a raucous protest outside the campaign's Manhattan headquarters in September. The protesters' lawyers have asked the Trump campaign to release its contracts for security, its guidelines for use of force, its security team's personnel records, and complaints against its members ? including for excessive force, assault, battery or "violation of any federal or state constitutional right."

Among Trump critics who've had run-ins with his security, complaints include unnecessary force, discriminatory profiling and removing people from events based on little more than their appearance. Some question whether the force's members are properly trained and certified for the work they're doing, while others assert that the force acts as if it has the power of the law behind it.

"It was this privatized mercenary force that seemed to have state sanctioning, and that's something that I haven't seen before," said Josh Jenkins, a Madison, Wisconsin, auto mechanic and veteran protester who served as the liaison with police at the Janesville hotel protest.

The Janesville Police Department eventually cleared the lobby, arresting six of the protesters and towing another's car, which was filled with supplies for planned protests the next day, deeming it suspicious because of an 8-pack of D batteries visible in the backseat. The department's deputy chief did not respond to questions about the role or conduct of Trump's security at the protest, or about why the car was towed.

But Jenkins, 45, said that Janesville police officers came across as the personification of professionalism and accountability, compared to Trump's security forces. The police officers introduced themselves to protesters almost as soon as they arrived on the scene and remained in communication throughout the four-hour protest. In contrast, Albracht and his associates did not identify themselves or give their affiliation, Jenkins said, adding that "their goal did not seem to be to de-escalate. Their goal was to escalate."