On this day, March 25, in 1975, Sheila Lyon, 12, and her 10-year-old sister Katherine vanished on their way home from Wheaton Plaza.

Their disappearance gripped the Washington region, leading to one of the largest police investigations in the area's history.

Witnesses saw Sheila and Katherine talking to a middle-aged man in a brown suit and carrying a briefcase outside the Orange Bowl pizza parlor at about 1 p.m. The man had a microphone and tape recorder, and the two girls were seen speaking into the microphone.

The sisters got a bite of pizza, eating together inside the restaurant, and were spotted walking toward their house between 2:30 and 3 p.m.

That was the last confirmed sighting of the Lyon sisters. Their case remains unsolved.

Anyone with information about this case should call the Montgomery County Police Cold Case unit at 240-773-5070.

-- Scott McCabe