CHESTERFIELD — An Anderson man who pleaded guilty to Medicaid fraud killed himself on Tuesday, hours before he was to report to a federal prison.

Chesterfield police were called to Ambulatory Renal Services, 232 Anderson Road, shortly before 8:30 a.m. and discovered Dennis M. Lennartz, 55, Anderson, inside a vehicle with its engine on parked in a garage, law enforcement officials said.

A hose had been extended from the car’s tailpipe and inserted into the passenger compartment. Officials with the Madison County Coroner’s Office have ruled Lennartz’s death a suicide. It will be several weeks before they have the results of toxicology tests and know the exact cause of death.

“It’s a tragedy for the family because he had a wife and three children,” said Jack Crawford, an Indianapolis attorney who represented Lennartz in the federal criminal case. “He never indicated during my time representing him any undue depression. It’s a shock. It’s a shock.”

It wasn’t known if he left a suicide note. A published telephone listing for Lennartz could not be found. It also wasn’t immediately clear if Lennartz’s death was directly linked to the impending prison term, but his attorney believes it’s likely.

“Certainly from the timing of it, it seems so,” Crawford said.

U.S. District Judge William T. Lawrence sentenced Lennartz on April 22 to three years and seven months in prison after Lennartz pleaded guilty to defrauding nearly $1 million in health care funds.

Lennartz pleaded guilty to one count of health care fraud for fraudulently billing the Medicaid program of about $965,000 between August 2006 and December 2008, federal officials previously said in a news release.

Federal prosecutors charged Lennartz in December. He faced a maximum sentence of 20 years in prison.

Lennartz was accused of using the Medicaid provider number for Wabash-based Waters Transportation, which provides transportation for patients to medical appointments.

In one case, he claimed to have transported a person receiving radiation treatments 300 miles per trip, when the distance was actually 31 miles. Another patient was taken to Riley Hospital for Children once per month, but Lennartz submitted billing statements claiming the person was taken 42 times over a three-month period.

Crawford said Lennartz was expected to report at noon Tuesday to the federal prison in Milan, Mich., about 45 miles south of Detroit. The prison houses minimum- to moderate-security offenders.

Crawford said Lennartz’s death is all the more surprising because Lennartz’s prison sentence was relatively short and he had served a previous prison term for defrauding Medicaid, which helps pay for the medical services of the elderly, disabled and needy families with children who don’t have health insurance.

According to court documents, Lennartz owned Ambulatory Renal Service when it was under investigation in 1987 by the Indiana Attorney General’s Office. The business took patients for dialysis treatment.

Prosecutors alleged he overbilled for mileage and time spent with patients while they underwent dialysis. The amount he took was not included in the court documents.