A federal appeals court has ruled that security company ADT and appliance maker Honeywell could not be held liable for an alarm system that failed to activate during the theft of a couple’s gun ultimately used to murder the mother’s son.

The U.S. Court of Appeals for the Third Circuit upheld the dismissal of Julie Heeter’s lawsuit against ADT and Honeywell. Heeter claimed that the alarm system’s failure to alert her of Cea Jay Chattin’s break-in of her and her husband Robert Heeter’s Columbia County weekend home made the companies partly responsible for the death of their son Bryan Harris.