The Far North Dallas psychologist said he treated a single postal worker seven days a week, up to eight hours a day. A federal billing contractor responded by paying the therapist more than $1 million, court records say.

Now Michael Ellis Wolf, 62, has pleaded guilty to a five-year health care fraud scheme and agreed to surrender his license to practice psychology. Authorities took him into custody today at the Dallas federal courthouse. He faces up to 10 years in prison, plus fines and restitution, at a sentencing hearing May 7.

There was no immediate word on how the scheme went undetected so long and whether others would face charges.

Court records identify the billing contractor as Affiliated Computer Services, or ACS, which processes workers compensation claims for the U.S. government. Xerox acquired it in 2010.

The records don’t name the patient, although they do say he was eligible for workers comp. He received therapy from Wolf once or twice a week beginning in 1996, and the fraudulent billing occurred from 2008 to 2013.

Follow @BrooksEgerton and @DMNInvestigates on Twitter. Like the DMN Investigates page on Facebook.