A propane leak likely triggered the explosion last week that killed Banner Creek Reservoir director Lu Griffiths and seriously injured his wife while leveling their home just north of Holton, Jackson County Sheriff Tim Morse said Monday. "It is unknown what the actual source was that ignited the explosion," he said in a news release. Preliminary investigation indicated the blast wasn't the result of a criminal act, he said. The Jackson County Sheriff's Office continued to investigate circumstances of the blast, which occurred about 6:15 p.m. May 10 at the house where Griffiths and his wife, Teri Griffiths, lived at 27284 Q.4 Road, more than three miles north of Holton.