Federal prosecutors are investigating what they call a massive scheme to illegally finance Sen. Susan Collins' 2020 reelection bid, Axios has learned.

What's happening: A recently unsealed search warrant application shows the FBI believes an executive with a Hawaii defense contractor illegally funneled $150,000 to a pro-Collins super PAC and reimbursed family members' donations to Collins' campaign. There's no indication that Collins or her team were aware of any of it.

• Collins helped the contractor at issue, then called Navatek, secure an $8 million Navy contract before most of the donations took place.
• The Navatek executive, Martin Kao, was indicted last year for allegedly bilking the federal government of millions in coronavirus relief loans.

The big picture: Federal prosecutors say Kao used a shell company to funnel $150,000 in Navatek funds to a pro-Collins super PAC called 1820 PAC.

• According to the FBI, Kao and his wife set up a sham LLC called the Society for Young Women Scientists and Engineers. Navatek then wrote the LLC a $150,000 check, investigators say, which was passed on to the super PAC.
• Government contractors are barred from donating to federal political committees, and investigators suspect the donations were attempts to evade that prohibition.

Investigators say bank records also show that Kao illegally reimbursed family members who donated to Collins' campaign, a practice known as a "straw" donation.

• Navatek reimbursed some of Kao's colleagues for their Collins campaign contributions, the FBI alleges.
• The donations came in clusters, according to federal contribution records, between June and September 2019.
• The warrant quotes an email exchange between Kao, who had just maxed out to Collins' campaign, and the senator's Maine finance director. "If you have friends or family members that would be willing to donate please don’t hesitate to send them my way," the Collins staffer wrote.

Read the search warrant application: