Blowing up your own house is one thing. Killing your neighbors while doing it is another.
An investigation led by local and federal authorities, including the Bureau of Alcohol, Tobacco, Firearms and Explosives, revealed suspicious behavior and circumstances surrounding the explosion. In particular, various elements of the gas line at Shirley's home may have been tampered with before the blast, including a missing step-down regulator, which reduces gas pressure entering the home, and a missing on/off valve to the residence's gas fireplace.
"The absence of the valve and regulator would explain how such a large volume of gas would be released into the home," Curry told CNN.
In addition, the digital thermostat at Shirley's home had been replaced by a slide-switch thermostat that "will produce a spark when the thermostat reaches a specified temperature," the probable cause affidavit says. However, it appears that the thermostat did not contribute to the explosion; instead, it appears to have been started by the microwave in the kitchen, which was a model that could be programmed to start 24 hours in advance.
Feel safer now, Max?