DALLAS (AP) — Four people from Texas have been charged in a $36 million health care fraud scheme as part of a larger nationwide crackdown.

The United States Attorney’s Office of the Northern District of Texas says 42-year-old Erik Bugen, 43-year-old Jody Sheffield, 41-year-old Matthew Hawrylak and 38-year-old Britt Hawrylak of Killeen-based ADAR Group were charged Thursday for allegedly participating in fraud from May 2014 to July 2017.

READ MORE: Driver Dies Crashing Head-On Into Pillar After Not Negotiating Curve In Road, Grapevine Police Say

Charges say the four had unnecessary and improperly prescribed toxicology and DNA cancer screening tests which were billed to military insurer TRICARE.

READ MORE: Allen Police Officer Forced To Shoot Aggressive Pit Bull

The investigation continues and is being conducted by the Defense Criminal Investigative Service, Veteran’s Affairs-Office of Inspector General and the FBI.

U.S. prosecutors announced Thursday that they’ve charged more than 400 people across the U.S. for their alleged involvement in health care fraud totaling about $1.3 billion in false billing.

MORE NEWS: Amazon Driver Shot After Witnessing Road Rage Incident, Fort Worth Police Say

(© Copyright 2017 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)