John Ingram Brandenburg of Chicago was identified by the Newton County Indiana Coroner's Office, with the help of the DNA Doe Project, through genetic genealogy.
Brandenburg was previously known only as "Brad Doe" after the remains were found off US-41 in Newton County in 1983, according to the DNA Doe Project.
All four victims are said to be of serial killer Larry Eyler, according to officials.
Only one of the victims still remains unidentified.
"We greatly benefited from their participation and involvement in our research process, and thank them for entrusting us with Brad Doe's case. Our hearts are with the family and communities affected by John's loss. It's for them that we commit ourselves to assisting law enforcement with these difficult identifications," said L. Elias Chan with the DNA Doe Project.