An Atlanta doctor allowed a drunk patient to get back behind the wheel, according to a lawsuit filed in Fulton County state court. Two hours later and several miles away, that patient caused a crash that killed the popular Cobb County author of "The Millionaire Next Door."

Now — in what one legal expert said is an unusual tactic — that doctor is being sued by the author's family.

Jeffrey Robert Fettig, 47, was being treated for alcoholism, anxiety and depression by Dr. Floyd Garrett, who prescribed Fettig the anti-anxiety drug Lorazepam, the lawsuit states. After being sober for six months, Fettig relapsed in February 2015 and made an emergency appointment with Garrett on a Saturday.

Fettig had already had five pints of beer when he arrived at the noon appointment on Feb. 28, 2015, according to the suit. Neither Garrett nor his attorney responded Wednesday to requests for comment on the case.

After the appointment, Fettig continued drinking, making two additional stops before attempting to drive home. Fettig was driving his Acura on Paper Mill Road near Atlanta Country Club Drive when his vehicle T-boned a 2012 Corvette driven by Thomas J. Stanley. Stanley, the author of the “Millionaire Next Door” book series, died from his injuries. He was 71.

Tests on Fettig's blood nearly two hours after the crash showed a blood-alcohol content of .192 as well as the presence of anti-anxiety medication in his system, according to investigators. Fettig later pleaded guilty to homicide by vehicle in the first degree and driving under the influence and was sentenced to 15 years, including eight to serve in prison.

But Fettig should not have been prescribed Lorazepam while he was drinking alcohol because mixing the two can cause the patient to black out or fall asleep, the lawsuit states.

The lawsuit seeks unspecified damages for wrongful death and requests a trial.