A spokesman for the Bureau of Alcohol, Tobacco and Firearms, which is investigating the Younkers fire along with the Des Moines Fire Department, refused to say Wednesday whether investigators were looking into Knapp. The cause of that fire, which caused the building to partially collapse, also remains unclear.
Henderson dismissed speculation about Knapp’s involvement in the Younkers fire, saying those suggestions were “pretty cruel” and Knapp may have already been dead by then.
The state medical examiner is awaiting the results of tests on Knapp’s blood for alcohol, drugs and other substances before ruling on the cause of death. Investigators have said that Knapp’s body didn’t have gunshot wounds.
Humphrey said investigators believe it’s possible the fire started accidentally if Knapp left the car running since it was in a timber area on top of dried leaves. Preliminary testing indicates Knapp didn’t die of carbon monoxide poisoning because the levels in his blood were not lethal, he said.
The fire also could have been started by Knapp or someone else inside the car, Humphrey said, but investigators found no lighter or matches.
While further testing of debris recovered from the scene is underway, Humphrey said it’s possible a definitive cause will never be known. Fires in vehicles can be difficult to investigate since they are filled with flammable liquids, he said.