(CNN) — Maryland police have made a breakthrough in a cold case going back to 1975, when two girls went missing, they said in a statement. They are looking at a convicted sex offender who was in the area at the time, but stopped short of calling the person a suspect.
Sheila and Katherine Lyon took a walk to a shopping center near their home in Montgomery County on March 25, 1975, and never returned. Police searched extensively for them but could not turn them up or solve the case.
Detectives have identified a convicted sex offender who was at the shopping center the day the girls disappeared. This person is currently behind bars and will be named by police Tuesday. Photos will be released.
Sheila was 12 and Katherine 10, when they went missing.
A witness saw them talking to a man holding a microphone the day they were abducted, according to a website dedicated to cases of missing persons.
The girls’ older brother also spotted them in a restaurant the same day, the CharleyProject.org reported.
Their brother, Jay Lyon, later joined the Montgomery police department as a homicide detective, the Washington Post reported in 1999.
The girls’ parents have placed a grave marker in a local cemetery with their names, dates of birth and the date they disappears, the Post reported.
If the girls are still alive, they would be 51 and 49 respectively.
–By Ben Brumfield and Dave Alsup, CNN