Investigators say Sunday's deadly fire in Emmaus, Lehigh County is not suspicious.
They have found no signs of criminal activity, police said Wednesday.
Investigators have confirmed the identities of the four people who were killed in that fire.
Montana Twining, 16, his mother, Melissa Twining, 48, her boyfriend, David Jenkins, 65, and Lena Marie Adamo, 56, died in the fire on South Fifth Street.
The coroner has completed autopsies on all the victims.
He says they died from smoke inhalation and burns.