he was now a full-fledged star. >> there's no way to prepare for it. in the beginning it's novel. but it's slightly uncomfortable. >> reporter: in 1989 "lethal weapon 2" became an even bigger hit than the original. >> can't you go any faster? >> reporter: there was a third -- >> step on it, there he is. >> reporter: then a fourth. >> who's this joker? >> i don't know. >> spokesman for the nra? >> reporter: the series eventually took in nearly $1 billion worldwide. >> i try to make it fun. if it's not fun to me, it's just not worth it. one has to enjoy one's craft. >> reporter: was that his reputation back then, fun, zany? >> i think he -- yes, but he also had a reputation of having a temper. richard donners, "lethal weapon "director, talked about that. there was an undercurrent in mel that could be very dangerous, very volatile. >> reporter: he admitted to you he gets pretty dark, pretty