In the small group of American volunteers battling ISIS alongside the Kurdish military in Iraq, “Mickey” is now an outcast. The ex-biker turned ISIS fighter is actually Michael Windecker, a convicted sex offender whose past has caught up to him, causing a rift with the other volunteers and a problem for his Kurdish Peshmerga commanders.

The Daily Beast previously reported on the Americans volunteering in Iraq. That article featured “Mickey” speaking about his frontline view of combat in Iraq but personal history was on his mind as well. “Look, we all have a past and I’m no different,” he said at the time. “I’m human. My criminal record back home has been cleared and I’ve served my time,” he told The Daily Beast.

But Windecker’s criminal record was more serious than he let on. His 28 arrests in Colorado include one conviction for third-degree sexual assault from 1994 when Mickey was 20. His victim was 14.

As “Mickey,” Windecker attracted fans. He, and other American fighters like him, give a stateside audience captivated by news of ISIS a clear image of the U.S. presence in a war where the military’s expanding commitment is harder to measure.

Compared to the airstrikes, political deals, and special operations troops who form the backbone of U.S. policy against ISIS, the handful of Americans in Iraq and Syria are highly visible. That doesn’t mean that the contributions of even the bravest and most altruistic volunteers actually amount to much. Windecker and other Westerners aren’t carrying the burden of fighting ISIS. That falls almost entirely to Kurds, Syrians, and Iraqis. Stories about the personal bravery of Americans, like Windecker’s or others offered by less compromised narrators, can confuse the starkness of a moral struggle against ISIS’s evil with the fate of a war that depends on a complicated tangle of alliances and interests and that shows no signs of ending soon.

The morning after the story featuring Mickey appeared in The Daily Beast, another American volunteer mentioned in the article contacted its author, Ford Sypher. “That Mickey character is a fraud,” Samuel Swann wrote to Sypher in a private note. Swann also called Windecker a “compulsive liar,” and said, “We knew something wasn’t right about him the first day.”

None of the Americans or Kurds who spoke with The Daily Beast about Windecker dispute his accounts of fighting ISIS. But several of the Americans said they had held him at a distance for weeks, suspicious of his past and worried by his reckless actions in combat.

Whatever his peers knew or suspected about Windecker, it didn’t surface when Sypher initially spoke with the other Americans fighting alongside the Kurdish Peshmerga and who have now cast him out. Swann was present when Windecker was interviewed by The Daily Beast but at the time did not express any doubts about his character. Neither did any of the other Westerners, mostly Americans, who spoke with The Daily Beast on the same day they saw Windecker being interviewed.

Confronted with the accusations against him, Windecker told The Daily Beast, “Anyone can go on the Colorado sex offender web site, but I have my paperwork to show my case is closed.”

That’s true. All 28 charges against Windecker are closed, according to a Colorado district court official. His arrests span 16 years. They range from domestic violence and weapons violations to the felony sexual assault charge, for which he was convicted and sentenced to two years. Windecker’s last arrest in Colorado was in 2010 for failing to register as a sex offender. He was fined $816.50 and sentenced to a year in jail.

General Tariq Hawleri, the Peshmerga commander who praised Windecker’s “ferocity” in battle when he first spoke to The Daily Beast, is more reserved now. “We were not aware of any criminal charges against Mickey,” Tariq said. “He is a volunteer and we thank him for volunteering, but we do not accept criminals. We will be looking into this.” Several of the other Americans who spoke with The Daily Beast about Windecker have already drawn their conclusions.

“Nobody wants him around at all,” Swann said. “We contemplated kicking his ass every day. Hope he goes to prison when he returns to the States. He’s a huge liability.”

Like the other Americans who have joined the Peshmerga, Windecker exists in a legal gray area. Secretary of State John Kerry has “the authority to revoke the passports” of any American citizen who travels to Syria to join armed groups.

In practice, the U.S. government is worried about jihadis returning to conduct terrorist attacks in the U.S., not the few dozen anti-ISIS crusaders like Windecker. But traveling to Iraq without the government’s protection forces volunteers like Windecker to rely on the Kurds who take them in, and perhaps most of all, on the trust and protection of the few Westerners who share their background. Windecker has lost that.

In every war, there are people who see opportunity. While other groups fight for conquest or survival, for people like Windecker, a far off battlefield can hold the promise of redemption or personal glory. Though that’s not how he described his motivations when he told The Daily Beast he traveled to Iraq, “for the people, nobody else. I’m here for all of those who want to live a peaceful life that has been deprived to them by ISIS.”

The only common trait among the Americans who have joined the war against ISIS is the large number who say they are veterans of the U.S. military. Windecker initially said he had served in the French Foreign Legion. But he backed off that claim, which was publicly disputed even at the time he made it, in a subsequent conversation with The Daily Beast. When asked to provide a, “direct yes, or no, regarding prior service in the [French Foreign] Legion,” Windecker became evasive saying, “Just put no on there I don’t need all my past issues jumping up.”

Even among the actual military veterans fighting ISIS there is no single explanation for what drew them there. Some may feel an obligation to the Kurdish people whom they bonded with on past deployments and see as staunch American allies now under threat. Others see a clash of civilizations or a biblical struggle between good and evil. There are war seekers, though hardly anyone admits to being a member, for whom a long peaceful American life sounds like a curse. And then there are those like Windecker who might have hoped that as “Mickey” the war in Iraq would allow him to escape or transform his past.

Last year, when Jordan Matson left Wisconsin to join the YPG, a Kurdish militia group battling ISIS in Syria, he became an early hero of the cause. Last September when photos of Matson began appearing publicly, he became a kind of heroic meme.

Stories spread on social media and new sites of the purportedly ex-Marine and “Conservative Bad Ass” fighting ISIS. The truth was more complicated. Matson had served in the military but in the Army rather than the Marines, where he’d been given an early discharge. The initial story touting a hardened combat veteran who had turned his sights on ISIS hid an earlier suicide attempt where Matson expressed anguish over being “railroaded out” out of the Army to police officers who found him with a loaded gun.

Matson never tried to hurt anyone but himself. But like Windecker, his journey to defend suffering people in Iraq started from a haunted past.

For Kurdish forces, like the Peshmerga and the YPG, who have welcomed them, Western volunteers may be useful as fighters but they also provide a constant spotlight useful for capturing media attention even when more dire local causes go unnoticed.

One American who had joined the YPG to fight ISIS in Syria left the group because he was treated more like a prop, he said after leaving the group.

The outcome of the war against ISIS depends on a number of things: Iraq’s ability to rebuild its military, American air support and special operations assistance, the direction of Iranian strategic planning, and the potential to reconcile anti-government Sunni groups to Baghdad and turn them against ISIS. A few dozen American volunteers, who might see some private or altruistic purpose in the fighting, won’t directly affect the war’s outcome one way or the other.

—With reporting by Ford Sypher and research contributed by Brandy Zadrozny.