A federal judge ruled that Kerr-McGee Corp. understated the value of the oil and natural gas produced from the leases, allowing it to pay fewer royalties than the government was entitled to, The Wall Street Journal said.
Anadarko Petroleum (APC) acquired Kerr-McGee in 2006.
Maxwell presented evidence that the company was understating production to his superiors. They believed there was no compelling evidence of fraud, leading him to sue on behalf of the federal government as a private citizen, under the False Claims Act.
Maxell is entitled to 25% of the settlement.
Gregory Goldberg, a lawyer for Kerr-McGee, said, "we respect the court's decision and are evaluating our options."