Person of Interest in Missing Lyon Sisters 1975 Cold Case

Maryland police ask public's help for any information about convicted sex offender Lloyd Lee Welch.
3:00 | 02/11/14

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Transcript for Person of Interest in Missing Lyon Sisters 1975 Cold Case
Good afternoon could become -- Montgomery county police department. On not march 25 197512. Year old Sheila Lyon and ten year old Kathryn Lyon left their home walked to nearby Wheaton plaza. The girls never returned home. This case shocked her community in 1975. And has never been forgotten by the police department or anyone who followed the case 39 years ago. Our cold case squad has been able to identify a man. Who is currently incarcerated as a convicted child sex offender and we've established that this man. Was at Wheaton plaza on that day and may have had contact with the line girls. The person of interest. Is Lloyd -- Welch also known as Michael -- Michael Welch. -- won't tell you what we know. And effort finish out of Philly you win on on details we've been able to establish. What -- then go and ask for. The public's help anyone's help who make you would fill in some of the blanks that. We're dealing with. Investigators have established the fact that Welch was at Wheaton plaza on March 25 1975. We've also established that Welch was observed paying attention. To the line sisters while at Wheaton plaza. Welch now has multiple convictions for sexual offenses against young girls and has been incarcerated. Since 1997. In the state of Delaware for one of these offenses. Welch has criminal convictions involving young -- victims in the states of Virginia Delaware and South Carolina. Although he is originally from the Washington DC area. -- has traveled extensively. Throughout the United States during the 1980s. And early ninety's. He was employed -- -- carnival company which traveled to various locations throughout the United States often setting up at shopping malls. Welch was a ride operator for the carnival. He also was accompanied in his travels. Was often accompanies travels by his girlfriend Helen -- -- also employed. By the carnival company. A picture. Helen and Welch are there. On my far. Left. We what. We're waiting room just. Publicly -- list. Nearly two dozen locations. Where we know Welch. Was. From 1974. Through 1997. A -- all of them but he. Not only was he in the DC area. Four. During the time the late seventies but we know that he was in north Miami Beach, Florida in 1980. He was in -- serrated in Marilyn from 82 to 84. He was in Los Angeles. In 1987. Sioux City, Iowa in 87. He was in a number of locations in South Carolina from 1988. Through 1994. He was back in Baltimore. In 1994. And in Pennsylvania. In 1994 he was also -- Prince William county in 1995. These. Locations and dates have been have been provided. In the reason I share that it's because it's important that. We. Try to determine if he may have been involved in any criminal activity. In any of those locations. During that time. And Welch was also arrested -- back in the mid seventies. For a burglary in Montgomery County on Hobson street which is just a few blocks away. From Wheaton plaza so you know that he was involved in criminal activity here at that time. We also know that Welch had some connection or was was seen. In the area. Surrounding the Walter the old Walter Reed annex. One forest -- -- seminary road many of you know that there's. Old castle church -- people used to call it. At that location and we know that he used to hang out in that area as well back in the seventies. He was known to -- right. Around the DC area. Spending a lot of time source -- in -- He was also known to walk along the railroad tracks from Kensington to silver spring. He's been over the the pass or were prior to 97. From the seventies to the ninety's he was also employed at various locations as a landscaper including his employment with the carnival. Much of the time during the seventies and eighties. Welch was considered a -- And is believed to have stayed in hotels. And homeless shelters. Now that's what we've been able uncover. -- -- cold case detectives have been able to establish. So we're looking for the public's help. Anyone who has any information about -- Welch that very likely could know him as Mike Welch an alias. Anyone that has information about him. During that time between the seventies in the ninety's. We can't we ask for them to contact. Law enforcement. Anyone has information about Helen -- -- we would ask information. Ms. -- is now deceased. But that anyone that had. Has it from him about. This scraper is asked to contact us. In addition we have established that one of the security guards at Wheaton plaza. Jobs one a security guard has been described as the captain of the security guards. On the phone that who was working there on the date of those lines girl's disappearance. We're also looking for information about the identities of any security guards. That were working. At Wheaton plaza during that time. All of the all of these folks we believe are all all of that -- -- the security captain. And anyone that would have information about. Lloyd Welch Mike Welch. Or Helen -- -- we believe could help us fill in some of the blanks and assist us. In it in. Determining more information about mr. Welch who at this point. Is is a person of interest in the case. I want to point to be the pictures on the on the my far right you've got picture. Welch. From a 1977. After an arrest. Be drawing that he sketch form that is to -- -- -- -- -- Picture. Is a crime. Is sketch that was done. An individual who a witness. At the time of the supplies girl's disappearance. Gave a description of a man that was following. And may have had contact. The -- sisters. So as you can see there certainly is a -- fairly strong resemblance between. The photo and and the sketch. So we've got. -- the the cold case squad. Has. Like like with all cases that we reopen. We have. Interviewed. -- witnesses that are still around from the original case we're looking at Newark new information always comes along. And certainly the fact that. Mr. Welch who we established was was at the scene. Looking at his criminal history since since that incident. Has made him. An important person of interest in this case.

This transcript has been automatically generated and may not be 100% accurate.

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