This workshop will present a case study and detailed timeline reviewing line-of-duty deaths (LODDs) that occurred while fighting a fire resulting from a lightning-induced failure of a corrugated stainless steel tubing (CSST) propane gas line. It will share a detailed forensic video timeline including a fire dynamics simulator, forensic electronic data, fire testing, and photographs of the fire scene to help you understand the ignition, fire growth, and floor collapse that ultimately led to a Mayday and LODDs. It is a collaborative effort among ATF’s Fire Investigation and Arson Enforcement Division (NCETR), the Fire Research Laboratory (FRL), and the Howard County (MD) Department of Fire and Rescue Services Office of Fire Marshal. Presenters include Special Agent ATF Adam St. John; Jeremy Neagle, P.E., Electrical Engineer, ATF Fire Research Laboratory; Captain Craig Matthews, Office of the Fire Marshal Fire Investigation Division; Celeste Flynn, Widow of Lt. Nathan Flynn, Phoenix Advocates; and Sara Laird, widow of BC Josh Laird, Phoenix Advocates