The Lethal Weapon TV series was a surprise hit, accurately mimicking the set-up of the popular Mel Gibson-Danny Glover film series it was based on. However, its ratings dipped after one of its protagonists was killed off. Martin Riggs' (Clayne Crawford) death came about following some behind-the-scenes drama that forced the producers to split up the show's star duo.
Source:https://www.cbr.com/lethal-weapon-why-how-clayne-crawford-riggs-died/