The link I gave related to Cynthia Anderson mentions that serial killers Nathaniel and Anthoney Cook (who are brothers) have been considered possible suspects in her disappearance, but neither of them have been ruled out. Both of them are currently serving time in prison for a string of murders committed during the 1970s and 1980s. It wasn't until the late 1990s when they were charged with their crimes. This would explain why the UM segment on Cynthia Anderson, which aired in 1989, made no mention of the Cook brothers.

The link is: http://doenet.tripod.com/287dfoh.html

Thanks for posting about this. This story has always haunted me and it's nice to have more information, even if it's not a conclusion.