COPS GET BREAK IN 1975 LYON SISTERS KIDNAPPING

Cops in Maryland are fingering a convicted sex offender in connection with the terrifying 1975 disappearance of two young sisters. The mystery has haunted the Washington area ever since.

The Lyon sisters -- Sheila, 12, and Katherine, 10 -- were on their way home from the Wheaton Plaza Shopping Center in March 1975 when they vanished. A composite sketch was widely distributed and tips flowed in, but the Lyon sisters were never seen or heard from again. 

 "It was just stunning. It could have been anybody's kids," said Charleen Merkel, a shopper at Westfield Wheaton who remembers the disappearance well.

They were last seen talking to an older man who had a tape recorder and briefcase. He was never located. 

The girls left their Kensington, Md. home on March 25, 1975 to walk the half-mile or so to Wheaton Plaza, now known as Westfield Wheaton mall. They were on spring break, and wanted to get some pizza for lunch and see the Easter decorations. They had less than $4 with them.

A friend of the girls saw them outside the Orange Bowl restaurant, with an older man who had a tape recorder and a briefcase, according to news and missing persons reports. A sketch of that man was made and distributed, but the man was never located. MORE FROM NBCWASHINGTON