Apparently he was ratted out by a colleague:
Dr. Bruce Lowman’s lawsuit claims that as many as two-thirds of the therapeutic cardiac catheterizations performed by Dr. James D. Johnston were medically unnecessary and done in violation of the law. The suit also claims the hospital and Johnson routinely billed Medicare for the unnecessary tests.
That led to the hospital raking in millions in improper billings and in turn rewarding Johnston with bonuses, the suit contends.
