Electric matches like the one used to set the fire are made in bulk for fireworks displays and media pyrotechnics. That means that they cannot be traced using serial numbers or even lot numbers as they are mass produced and often done so in nations like China, Vietnam and Malaysia.
Rick Zainer says that he can't discuss anything he saw or heard while in the employ of Mr. Sternman because he singed a non-disclosure agreement. In reality there is no private NDA that can legally prevent someone from giving information to the police related to a criminal investigation, especially a homicide, or from testifying about their knowledge of criminal activity in a court of law (a common Law & Order mistake). Since Zainer was Sternman's nurse HIPPA laws would prevent him from discussing anything related to Sternman's health and his duties as a nurse without the police or the DA having a warrant, but the NDA could not legally prevent him from testifying to anything he heard or saw that was unrelated to Sternman's health or his duties as a nurse.
A skilled arsonist would not obtain his or her materials in a manner that would lead anyone back to them. They would purchase them from online, out of state or even from locations that would accept cash payments.
It would have been impossible to track the arsonist from his purchases.
It would have been impossible to track the arsonist from his purchases.