The physician swept into Terrell as a savior, rescuing its only hospital from bankruptcy. It was the summer of 2008, and Dr. Tariq Mahmood, a specialist in buying financially ailing hospitals, maneuvered swiftly to lay down the favored bid. Not everyone was swooning, however. As Mahmood took over Renaissance Hospital Terrell, employees grew alarmed by his practices. At least one hospital official alerted authorities. But her complaints went nowhere. It took regulators more than four years to rein in Mahmood. Before they acted, he allegedly submitted more than $1 million in fraudulent billings to the government, and substandard care at his chain of small-town Texas hospitals led to multiple patient deaths.