William Farwell admitted in police interviews that he had a sexual relationship with Birchmore for about two years when she was an adult and had sexual encounters with her in 2020 before her death.
Investigators are looking for Luis Francisco Soriano—also known as Jeffrey—who they believe fled to Puerto Rico following the murders and arrest of his alleged accomplice and brother, Julio Cesar Pimentel Soriano.
The family's bodies were found in a fire at their Knapp Avenue home on August 31.
Vermont State Police identified the victims as town boardmember Brian Crossman, 46, Erica Crossman, 41 and Colin Taft, 13, according to the Associated Press.
