Billie and Mary Lou Black

A Silver Alert is a public notification system in the US that broadcasts the details of missing senior citizens, particularly those with dementia or Alzheimer's disease. Research has shown that six in ten of those with Alzheimer's will wander off at least once. If they aren't recovered within 24 hours, the results can be fatal.

In Kansas, the state's first Silver Alert was triggered on 12 September 2009, when 74-year-old Billie and 72-year-old Mary Lou Black vanished from their Atchison home. It was 8:15 in the morning on 11 September when the couple drove off in their light blue four-door 1990 Honda Civic. The following day when he wasn't able to get hold of them, the Black's son Kurt went to check their house. Inside he found their drivers licenses, a checkbook and cash. In the fridge was Billie's insulin, which he had to take every day. He had quite severe diabetes, and had trouble both seeing and walking.

The Blacks had been married for more than 50 years. Billie was in the Air Force, and had been an electrical engineer for many years before moving on to home remodelling. Mary Lou was a teacher, and did clerical work for an insurance company before retiring in 2002. Some years later, however, she began to suffer from Alzheimer's disease, and would occasionally wander off from their marital home, walking up the residential street and looking into people's mailboxes. Sometimes she would let herself in, sit down on the sofa and say, "I'm home".

Despite searching by air and foot, police were unable to find any trace of the couple or their car. And though numerous sightings were called in, but none of them could ever be verified. After a couple of days with no sighting of Billie and Mary Lou Black, rumours began to swirl that perhaps their disappearance was deliberate. The couple were in ill health, and Billie had once remarked to Kurt when they went to look at a nursing home that it would be better if he and his wife weren't around. Billie knew all too well what awaited Mary Lou. He had seen his own mother and mother-in-law suffer from the disease too.

Police now suspect that Billie deliberately drove their car into the Missouri River. In the years that have passed since the Blacks vanished, the police have dredged the river and nearby lakes on numerous occasions. Though they have found several cars during their searches, none of them belonged to Billie and Mary Lou Black.