Authorities say harvesting the innards of flares and using them to make explosives that are later sold is illegal. More photos with the Popular Science story showed additional evidence of illegal activity, according to court records.

Miller was also the subject of a Minnesota Department of Natural Resources investigation into a wildfire that started March 23, 2019. According to court records, the fire occurred near Miller’s property on 3392 County Road 249 in Brownsville, and the DNR investigator saw numerous parachutes like the ones used in Miller’s rockets both in the trees where the fire started and on Miller’s land.

Miller told authorities that his teenage son started the fire while playing with a plastic 12-gauge flare gun.

Miller also told investigators that he sells his products privately and to a gun show dealer, but that he does not have a website “because he does not have the organizational skills,” according to court records.

Miller also was investigated in 2000 after his employee, Howard Snelson, died as a result of an explosion due to smoke inhalation and thermal burns.