The abduction of Sheila and Katherine Lyon in 1975 had a dramatic impact on the D.C. region.
The girls were 12 and 10 years old when they vanished while visiting the Wheaton Plaza shopping mall.
Fear ran high in Montgomery County where it changed the way people raised their children.
"The disappearance of the Lyon sisters was so traumatic that it changed every parent's way of looking after their children. The innocence of playing in neighborhoods totally changed," said Don Hoage who raised his children in Kensington.
"I use to keep my front door open. Kids would run in and out, in and out. I didn't' keep it open after that," said Shirley Yania who lives in Kensington with her husband John. Their daughter Sherry was friends with the Lyon sisters.
"We wouldn't let them go out alone, she wouldn't go out, actually she was afraid," said Shirley's husband John Yania about their daughter Sherry.
"I just had to sit down and have a big conversation with her. And say, 'Sherry, this is how it is. This is what happened. You cannot talk to anybody that you don't know,'" said Shirley.
"It did change this place," said Bernie Bloom who now lives in Silver Spring but lived in Kensington where he was raising his children when the Lyon sisters disappeared.
When Lloyd Welch was charged with murdering the Lyon girls, Bloom says he felt like he could finally exhale.
"So it must've stayed with me for a long time."
And now that Welch has pleaded guilty and has been convicted?
"It's a good day for this community," said Bloom.
"Big relief. And I feel mostly for the parents. I mean to live through that for that many years, I don't know how they did it. Even for the kids that grew up with them. My daughter, she hasn't gotten over it. She needed to know that somebody has been found and convicted."