First, there was the role of Rick Rivers in 1989's "Fire Burn, Cauldron Bubble." An unscrupulous writer (played by Brad Dourif - Wormtongue. WORMTONGUE!) descends on Cabot Cove to drum up interest in his book about a long-dead Cabot Cove witch (Cabot Cove had witch trials, just as it had the Battle of Cabot Cove during the American Revolution). He has employed a sneaky, unscrupulous, ferrety young media consultant - Rick Rivers - to stage mysterious events in order to make people care more about witches and snooty authors in hats. Someone dies; people are extremely perplexed; Jessica notices something and later remembers noticing it; she identifies the murderer; the murderer inexplicably confesses.
Then, there was the role of Frank Albertson in 1990's "Good-bye Charlie," an episode I've already discussed, because Bryan Cranston was also in it. Frank Albertson is a sneaky, unscruplous, ferrety young man who decides to identify a random corpse as his uncle in order to claim an inheritance. Someone dies; people are extremely perplexed; Jessica notices something and later remembers noticing it; she identifies the murderer; the murderer inexplicably confesses.
Both roles, as I have already suggested, required an actor capable of conveying a particular kind of sneakiness, unscrupulousness, and ferrety-ness. Both roles also required an actor capable of cultivating a particularly luxuriant, era-specific hairstyle. As Dean Stockwell was too old and shunned mullets, both roles went to Bill Maher.
Here he is in action on Murder, She Wrote, saying only "wallet."