WASHINGTON >> The FBI has been reviewing a possible scheme to funnel illegal donations to the 2020 reelection campaign of U.S. Sen. Susan Collins, a Maine Republican, recently unsealed court records in Washington, D.C., show.

The FBI is investigating whether Martin Kao, former chief executive officer for Hawaii-based contractor Martin Defense Group, illegally donated money to the senator’s campaign, according to a search warrant application filed in federal court in April. The contractor has offices in Maine as well as other locations.

An FBI agent alleged in a court affidavit that Kao used a shell company to make a $150,000 donation to the campaign and reimbursed family members for smaller donations to Collins. Under federal law, government contractors are prohibited from making donations to political committees. So-called “straw” donations in which a contributor uses someone else’s money are also illegal.

Annie Clark, a spokeswoman for Collins, said the senator’s campaign “had absolutely no knowledge of anything alleged in the warrant.”

A lawyer for Kao did not immediately respond to a request for comment.

The donations to Collins’ campaign under investigation were a small percentage of the more than $30 million in receipts her campaign raised in the last cycle. Outside PACs on both sides spent many millions more in one of the most expensive Senate races in the country.

In August 2019 Collins announced that Martin Defense Group, then known as Nava­tek LLC, had received an $8 million Department of Defense contract. A news release on her website said she “strongly advocated” for the funding.

Kao, a prominent Hawaii defense contractor, was indicted last year on charges that he bilked the federal government out of millions of dollars in coronavirus relief aid intended for small businesses.

Authorities say he defrauded banks of more than $12.8 million through the Paycheck Protection Program. He also transferred more than $2 million into his own personal accounts, according to an indictment. Investigators talked to an executive and a former employee who said the company wasn’t affected by the pandemic, court documents said.

Kao stepped down as CEO in November.