The Justice Department announced criminal charges Tuesday against 455 people as part of a two-week healthcare fraud crackdown that officials say involved more than $6.5 billion in false claims submitted to insurers.

Among those charged is a nurse practitioner accused in Texas of billing Medicare for medically unnecessary wound-care procedures and using the proceeds for fancy jewelry and luxury cars; a mental health company owner who prosecutors say targeted the homeless by billing for crisis stabilization services they did not receive; and a hospice owner alleged to have paid kickbacks to a funeral home employee for information about deceased Medicare beneficiaries.

A heart doctor, meanwhile, is charged in Florida in an $89 million healthcare fraud scheme, accused of billing insurers for medically unnecessary cardiovascular screening tests for college student-athletes and then rubber-stamping the results as normal without personally reviewing them.

The doctor, Jason Finkelstein, 53, faces charges of healthcare fraud and conspiracy in what prosecutors describe as a yearslong scheme that preyed on the fears of athletes that they could die on playing fields or courts of sudden cardiac arrest. Athletes with no preexisting conditions who were concerned about being cleared to compete were administered tests they did not need and, in one case, a patient whose results were falsely certified as normal later died after his significant heart problems were undetected, the indictment says.

Healthcare fraud has been a long-running Justice Department priority and news conferences announcing roundups and crackdowns have been common occurrences across the years. The Trump administration has made a point of emphasizing enforcement over the last year, including through the appointment of a new assistant attorney general, Colin McDonald, to help oversee healthcare fraud prosecutions at a Justice Department that operates multiple specialized task forces.