Three Hawaii defense contractors were indicted Thursday on charges that they made illegal campaign donations to U.S. Sen. Susan Collins through a shell company, the U.S. Department of Justice announced in a press release.

Martin Kao, Clifford Chen and Lawrence Lum Kee allegedly funneled funds from their contracting business through a company that donated money to a political action committee supporting Collins’ campaign. The DOJ also alleges that the trio of defendants used their family members to make illegal campaign contributions.

Kao, Chen and Lum Kee are all accused of conspiracy to defraud the U.S. Kao is also charged with two counts of making false statements to the Federal Elections Committee.

Kao was recently charged with defrauding the federal government of Covid-19 relief money.

If convicted, each defendant could face sentences of up to five years in prison and fines of $250,000 for each count.

The defendants have not yet made their initial appearance in court, according to the DOJ.

The Martin Defense Group, which Navatek is now called, has earned millions in dollars in defense contracts. Employees of the company have donated heavily to Collins’ campaign and others. Last May, unsealed court records detailed how the defendants reimbursed their family members for donations to Collins’ campaign.

Kao has been a prolific political donor in years past. His company, which designs hulls for ships, has secured millions of dollars in federal contracts over the years.