Mary Lou Sena was 9 when she and her 11-year-old cousin Billy Sena were last seen on September 22, 1979, in the Martineztown neighborhood of Albuquerque. The children left their home about 10:00 a.m. to go to the post office and play on the nearby grass and never returned. Their whereabouts remain unknown and the case is listed as a non-family abduction.

Over the years several theories have circulated, from the possibility the children were accidentally locked in a railcar to suggestions they were abducted, buried in a basement, or ran away. In 2011 authorities named Michael Cordova, who lived with Billy’s family in 1979, as a person of interest; reports say he had severely beaten Billy shortly before the disappearance. Another woman who lived with the family in 1979, Liza Ramirez, has also been sought but both have remained untraceable in relation to the investigation.

Many family members who remember the children have since died and the families still seek answers. Anyone with information about Mary Lou or Billy’s disappearance is urged to come forward.