UnitedHealth confirms it has opened a federal investigation into its billing fraud.

The U.S. health insurance and healthcare products company UnitedHealth Group confirmed Thursday that the U.S. Department of Justice has opened several civil and criminal investigations into fraud in its billing activities.

"The company has already begun complying with the Department's formal requests for criminal and civil matters. The company is fully confident in its practices and is committed to working closely with the Department throughout this process," the company said in a statement .

It also stated that, "to provide transparency and trust" in its business practices, it has launched its own internal initiative "to conduct third-party reviews of policies, practices, and processes."

Specifically, the Department of Justice is investigating the group for possible fraud in its Medicare Advantage program. The private company is one of several insurers that participate in the U.S. government's Social Security coverage program for people 65 and older and other beneficiaries.

This comes after Andrew Witty, its former chief executive, resigned for "personal reasons" following the suspension of its financial guidance for this year, citing higher-than-expected costs for its Medicare program.

Brian Thompson, CEO of UnitedHealthcare, the insurance unit of UnitedHealth Group, was shot and killed in December 2024 near the Hilton Hotel in midtown Manhattan, New York, as he was preparing to attend the multinational's annual investor conference.

Luigi Mangione, the 26-year-old accused of killing him, pleaded not guilty last April to all charges, including murder, after the U.S. Attorney's Office formally requested the death penalty against him.

The young man, who was arrested in December 2024 at a McDonald's in Altoona, faces additional state charges in New York and Pennsylvania related to his flight from the crime scene.

Investigators suspect Mangione acted out of resentment toward the U.S. health insurance industry , which has been repeatedly accused of rejecting its own clients' claims almost entirely.