This year marks the 25th anniversary of a few Unsolved Mysteries cases. The dates next to the names are the dates when the disappearances/murders/offenses happened, not when they aired on TV. Let me know if I missed anybody.

Wil Hendrick (missing, later found deceased, January 10, 1999)
Damien Corrente (murdered, January 14, 1999)
Jason Horsley (shot and killed by his racist neighbor Malaika Griffin, May 18, 1999)
Dale Williams (missing, May 27, 1999)
Lisa Ann Myers Neugent (missing, September 8, 1999)
Jean Weaver (murdered by her husband Gordon, October 16, 1999)