The body of Bobby Joe Knapp, the Greater Des Moines developer who was recently released from prison after pleading guilty to violating the federal Clean Air Act, was found Sunday in a burned-out car that had been set ablaze in a Guthrie County farm field.

An autopsy was conducted today, but the “cause and manner” of Knapp’s death are under investigation, according to a release from the Iowa Department of Public Safety.

 The Business Record has been told that Knapp’s body did not have any burn marks. Knapp, 64, was released from a federal prison near Duluth, Minn., on Tuesday March 25.

He did not report for an automatic check in with the U.S. Marshall’s office the next evening. The office had issued a warrant for parole violation after Knapp failed to check in.

“The subject was also suspected in driving a Honda Accord that was reported stolen by the Waukee Police Department,” according to the release from the Iowa Department of Public Safety.

The car in which Knapp’s body was found had been reported stolen, according the Department of Public Safety release. Knapp owned and was renovating the Equitable Building in downtown Des Moines when state and federal investigators determined that he had violated work practice standards between 2005 and 2008.

He had denied any wrongdoing in the case, but entered a plea agreement with federal prosecutors in March 2011. He was sentenced to 41 month in a minimum security prison in June 2011.

In the plea agreement with federal prosecutors, Knapp admitted that he conspired with Russell Coco, who was also charged and pleaded guilty to the same counts on February 2011, to remove materials containing asbestos from the Equitable Building without complying with the requirements of the Clean Air Act prior to starting the renovation.

Testimony during Knapp’s sentencing hearing showed workers were not given protective equipment and that workers and tenants were exposed to large amounts of asbestos dust during the renovations. After financial markets collapsed in 2008 and during the asbestos investigation, Knapp attempted to transfer many of his far-ranging holdings to his children.

However, many of those properties were saddled with debt, which the children had to resolve. Among the problem properties was Suites of 800 Locust, which Knapp renovated into an upscale hotel.

His children sold the property last year to Rebound Hospitality of Northfield, Minn., and it is now called 800 Locust Hotel and Spa. Polk County property records also show he accrued about $300,000 in state tax liens for failure to pay sales taxes that were generated by transactions at the hotel.

Those liens were released in June 2012 after the taxes were paid, according to a filing with the Polk County recorder.