Yeah, I would call that a “killer of the week” format. There is a new crime/murder every week. Sometimes there is a season-long story as well (Natasha Lyonne’s character running away from the Vegas baddies) and sometimes it’s just the killer of the week story. Murder, She Wrote is a good example of the latter; you can watch MSW episodes in pretty much any order, it doesn’t matter because each episode is basically self-contained. Any story external to the killer of the week is just to service actors being replaced or setting Jessica Fletcher in different locations beyond her hometown so she can face a new killer of the week. MSW is a whodunnit and also a killer-of-the-week show.