Lyon sisters

Katherine Mary Lyon (aged 10), and Sheila Mary Lyon (aged 12) were sisters who disappeared without a trace during a 1975 trip to a shopping mall in the Maryland suburbs of Washington, D.C.. Known colloquially as The Lyon Sisters, their case resulted in one of the largest police investigations in Washington Metropolitan Area history. It has long been "one of the most high-profile unsolved cases in the D.C. area." The girls' remains have never been found.

In 2013, a team of cold case investigators with the Montgomery County, Maryland, police made a break in the case. They focused on Lloyd Lee Welch, by then serving a lengthy prison sentence in Delaware for child sexual abuse, the culmination of a long criminal record that had begun a few years after the girls' disappearance with a burglary arrest in their jurisdiction.

Police records show that during the original investigation, Welch came forward a week after the girls' disappearance and falsely told a security guard at the shopping center visited by the girls (immediately before they disappeared) that he had witnessed another man abduct them there. The description Welch provided of the other man matched a description that newspapers and other media already had provided the public. According to that description, a conservatively dressed man had demonstrated a new type of audiocassette player at the shopping mall as children and teens, including the Lyon sisters, gathered near him. A short time after Welch told this story to the mall security guard trying to cast suspicion on the other man, he was questioned at a police station, failed a lie detector test, admitted he had lied, was released and was not questioned again until more than 38 years later.

During the reopening of the case, police discovered that a mug shot taken of Lloyd Welch in 1977 bore a strong resemblance to a police sketch of a possible suspect who had been seen staring inappropriately at the Lyon sisters in the shopping mall. Detectives began interviewing Welch in prison; he made statements that further implicated him although he continued to protest his innocence. One of his relatives told them he had helped Welch burn two heavy, bloodied duffel bags in Bedford County, Virginia. In July 2015 Welch was indicted and charged with the girls' murders there; his uncle is a person of interest as well.

...
Wikipedia