This was a significant local event for the time and a long-running area mystery/cold case.
http://www.wbaltv.com/article/latest-man-pleads-guilty-in-1975-deaths-of-lyon-sisters/12227563
Quote
The Lyon sisters' disappearance shattered the sense of security in Kensington, Maryland, rattling parents to the point where they no longer let their children play outside or walk to Wheaton Plaza.
"It deeply affected everybody in a very large radius within the D.C. suburbs. People always wanted to know who did this, who was this person, what happened?" said Teresa Brookland, a former schoolmate who remembers Katherine as sweet and friendly.
Harry Geehreng, a retired Montgomery County police sergeant who searched the mall and surrounding woods for the sisters after they disappeared, said it took a couple of days for it to sink in that the girls may have been abducted because it was a sleepy area with little crime back then.
"It was just an innocent time and people never thought the worst," Geehreng said. "Just the idea that a total stranger absconded with these two little girls, it was really beyond belief. People were genuinely shocked."