Investigators have released the cause of a house fire that killed two people in Waterloo last month.

According to Waterloo Fire Rescue officials, an accelerate was involved in the deadly fire at 536 Dawson Street that claimed the lives of 32-year-old Ashley Smith and her 9-year-old son, Jaykwon Sallis on April 22nd.

Two others were treated for minor injuries at a local hospital. Investigators revealed on Monday that a Waterloo Fire Rescue dog was alerted to the presence of an accelerate during the investigation. The city’s fire marshal submitted that evidence to the Iowa State Crime Lab, which determined that a flammable substance was involved in the fire.

No charges have been filed in the case, which remains under investigation.

(By Elwin Huffman, KOEL, Oelwein)