Lyon Sisters case: Lloyd Lee Welch, Jr. 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/WJLA) - Police in Maryland say a convicted sex offender currently imprisoned in Delaware has emerged as a person of interest in the 1975 disappearance of two young sisters who never returned home from a shopping mall.

Sheila and Kate Lyon were 12 and 10 years old when they vanished on March 29, 1975. It was 39 years ago, but Marty Rutherford remembers it like it was yesterday:

"I remember seeing Kate and Sheila walk up the street that morning -- they used to deliver our newspaper."

The girls walked from their house through their neighborhood to Wheaton Plaza – but they never made it home. What happened to the sisters remains one of the most notorious crime mysteries in our region, and many say it ended an age of innocence.

Now, after all these years, police say 57-year-old Lloyd Lee Welch may be their abductor. Just look at this mug shot of Welch from 1977 compared to a suspect sketch from 1975.

Montgomery County Police Chief Thomas Manger explained, "Welch was at Wheaton Plaza on March 25, 1975. We've also established that Welch was observed paying attention to the Lyon sisters while at Wheaton Plaza."

Welch was a traveling carnival worker, and has multiple convictions for sexual offenses against young girls. He is currently in prison in Delaware for child molestation. He is not currently cooperating with detectives, so police are releasing his image in hopes that somebody remembers something.

They are also distributing a photo of Helen Craver, another carnival worker who was Welch’s girlfriend at the time. But police need more evidence, otherwise the case may be at a dead end.

Chief Manger says generations of detectives have never given up, while Rutherford always hoped the mystery would be solved.

However, she has been disappointed by false leads in the past, and fears it will happen again: "If he did it, he's gonna get away with it -- he has for 40 years."

The National Center for Missing and Exploited Children says you never stop digging – its oldest case dates back to 1938.

So where might the best tip come from? According to Executive Director Robert Lowery:

"It could be other potential victims, acquaintances of this suspect, a neighbor, someone who knew him very well...Someone who may have just seen this individual."

The Lyon family has released a statement, which includes the following:

"The fact that so many people still care about this case means a great deal to us...We are grateful for any information the public can provide to help us bring this story to its conclusion."