Forty years after Katherine and Sheila Lyon went missing in Maryland, police believe that they’ve found the man who allegedly abducted and killed them.

While the bodies of the sisters, who were ages 10 and 12 at the time of their abduction, have never been found, a Virginia grand jury decided there was enough evidence to indict Lloyd Lee Michael Welch, Jr. for the girls’ abduction and murder. Welch was easy to find: He is currently serving time in Delaware for two counts of felony murder.

The girls went missing after a trip to Wheaton Plaza Shopping Center on March 25, 1975. Investigators say that Welch, a convicted sex offender who worked for a traveling carnival, was at the same mall that day. He told detectives that he left the mall with the girls, but that his uncle is the one who molested them. He claims to have never seen them after that.

Statements from family members helped break the case after so much time–but Montgomery County police made statements indicating that other people may have known what happened to the girls. “We believe that there are people that have information, that knew about what was occurring,” said Montgomery County Police Chief Tom Manger. “That was criminal behavior on their part, not coming forward.”

Virginia is seeking to extradite Welch from Delaware so he can go on trial for the abduction and murder charges.