Lyon sisters disappearance cold case could break open with new person of interest

Katherine Lyon, left, and her sister Sheila Lyon, right, were last seen leaving to walk to Wheaton Plaza Shopping Center in Montgomery County in March of 1975.

GAITHERSBURG, Md. (AP) - Police in Maryland say a convicted child sex offender has been identified as a person of interest in the 1975 disappearance of two sisters who never returned from home a Montgomery County shopping mall.

County police said Monday the person they want to question is imprisoned in another state and had traveled extensively around the country.

Authorities expect to release more information at a news conference Tuesday, including about why the man is considered a person of interest. Police are also seeking the public's help to learn more about the man.

The announcement could represent a significant break in the investigation into the disappearance of 12-year-old Sheila Lyon and her 10-year-old sister Katherine. The girls went missing after walking to a nearby shopping center, then known as the Wheaton Plaza.