Erik Prince—the notorious former head of Blackwater, a military contracting firm blamed for the killing of Iraqi civilians—is all aboard the Trump Train.

He’s done several interviews on Breitbart News’ SiriusXM show over the past few months boosting the candidate, and newly released FEC filings from a pro-Trump super PAC show he made a generous contribution to their efforts. According to the Wall Street Journal, that PAC is helmed by Rebekah Mercer, the daughter of reclusive hedge fund billionaire Robert Mercer.

The September filings for the Make America Number 1 PAC, filed with the FEC on Oct, 20, disclose that one Erik Dean Prince of Middleburg, Va. gave $100,000 to the group on Sept. 21 of this year. Frontier Services Group, a security contracting company whose board he chairs, didn’t respond to a request for comment on Prince, who the Washington Post notes is a part-time Middleburg resident. And it’s technically possible there are two Erik Dean Prince’s living in Middleburg (pop.: 751) who really love Trump. But, well, unlikely.

Only seven people cut checks to Make America Number 1 in September. Prince’s was the second-largest (Bernie Marcus, the co-founder of Home Depot, gave the largest, $2 million). His mom, Elsa Prince, also gave $50,000 in September.

Prince’s contribution is interesting because he’s one of the most controversial figures of the Iraq War––a war that Trump now regularly repudiates on the stump. Prince founded Blackwater, a private security firm that contracted with the U.S. military in Iraq during the war there. In 2007, Blackwater employees were involved in a mass shooting there that left 17 civilians dead, including two boys, age 9 and 11. Nicholas Slatten, a former Blackwater employee involved in the shooting, was convicted of first degree murder and sentenced last year to life in prison. Three other former Blackwater employees were convicted of manslaughter, and received 30-year sentences. All four men are appealing their convictions. The shooting was one of the darkest moments of the war and changed the public debate over the U.S. military’s growing reliance on private contractors.

He previously gave the Mercer’s super PAC $50,000 on Aug. 21. The Center for Public Integrity notes that Kellyanne Conway, now Trump’s campaign manager, oversaw the super PAC’s activities when it was called Keep the Promise 1 and boosted Ted Cruz. But when Cruz conceded defeat, the Mercers changed its name to Make America Number 1. Then Conway left the super PAC and David Bossie––on leave from Citizens United and currently Trump’s deputy campaign manger––oversaw it for a bit.

Make America Number 1 isn’t the only pro-Trump, Mercer-affiliated outfit that Prince has a relationship with. Over the past few months, he’s made numerous appearances on the Breitbart’s SiriusXM radio show, praising Trump and sharing conspiracy theories about top Clinton aide Huma Abedin. Politico reported last year that Robert Mercer is a major investor in Breitbart News. And numerous outlets have reported that Rebekah Mercer is very close with Stephen Bannon––formerly the head of Breitbart and currently Trump’s campaign CEO.

Breitbart is now re-introducing Prince to a new generation of conservative media consumers. On a Sept. 8 appearance on Breitbart’s SiriusXM morning radio show, Prince said Trump’s idea to take Iraq’s oil as repayment for deposing Saddam Hussein is not a bad one.

“For Mr. Trump to say, ‘We’re going to take their oil––certainly we’re not going to lift it out of there and take it somewhere else, but putting it into production, and putting a tolling arrangement into place, to repay the American taxpayers for their efforts to remove Saddam and to stabilize the area, is doable, and very plausible,” he said.

On an Aug. 10 appearance on the podcast of Milo Yiannopoulos––a Breitbart writer who has praised racist alt-right writers as “fearsomely intelligent”––Prince said that the fact some of Trump’s companies have gone bankrupt is good.

“I even like some of his projects that have gone bankrupt, because people that do things, and build things, and try things, sometimes fail at doing it, and that’s the strength of the American capitalist system,” he said.

Yiannopoulos also told Prince he has a large gay fanbase.

“I’ve been thinking with some friends recently that we should do a sort of high fashion shoot, basically in Blackwater-esque gear, with Trump militia on flags,” he said.

It’s worth noting that Prince is a vice president of his family’s foundation, the Edgar and Elsa Prince Foundation, which gave more than $1.5 million to the Family Research Council from 2014 to 2014, one of the groups that has worked hardest to oppose gay rights.

And on an appearance on Breitbart’s radio show on Sept. 8, Prince shared the conspiracy theory that Huma Abedin is a covert member of the Muslim Brotherhood.

“She’d have a very difficult time passing any actual quality security background check on agents of influence,” he said. “It’s extremely troubling, and it’s amazing for Hillary, that purports herself to be a feminist and a great supporter of women’s rights, to at the same time have an adviser whose own view of the world is so anti-woman.”

Hillary Clinton and her affiliated super PAC, Priorities USA, have wildly outraised Trump and his allied groups over the course of this election cycle. The Mercer family’s support has played a major role in boosting Trump’s drab electoral prospects––and Erik Prince has been a small part of that.