More than 42 years after Sheila and Katherine Lyon vanished from Wheaton Plaza, Lloyd Lee Welch was set to go on trial for their murders in remote Bedford, Virginia. Would the Lyon family finally get the answers and justice they've sought for decades?

Lloyd Lee Welch will go on trial in September 2017 for the murders of Sheila and Katherine Lyon although their bodies have never been found. Investigators finally believe they know what happened to the young sisters who vanished almost 40 years ago.

Almost 40 years after Sheila and Katherine Lyon disappeared, a man was indicted for their murders. The indictment showed how close police had been to catching the suspect and the crucial mistakes that let him remain free for decades.

After years of frustration, investigators named a person of interest in the Lyon sisters' disappearance - an accused serial killer who had moved to Montgomery County soon before Sheila and Katherine disappeared, and who left after another young woman was brutally attacked.

The last people to see Sheila and Katherine Lyon in March 1975 paint a vivid picture of the young sisters' final hours before they vanished during a visit to the Wheaton Plaza shopping mall.

Sheila and Katherine Lyon vanished exactly 42 years ago on March 25, 1975. Their abduction shocked the Washington, D.C. area. In this podcast extra, we look at some of the challenges that existed in searching for missing children in the 1970s, as well as some of the improvements and tools available today.

Most people who have spent any time in the Washington, D.C. area in the past four decades have heard about the disappearance of Sheila and Katherine Lyon. The daughters of a popular local radio broadcaster walked to Wheaton Plaza mall on March 25, 1975, to see Easter decorations and have lunch. They never made it home. In episode 1, we hear moment-by-moment recollections of what happened that fateful day and recall the initial steps of the police investigation.

A preview of what to expect in the new WTOP podcast series, The Investigation Continues: The Lyon Sisters.