A mutant encountered in the Museum does not have to die. When we get to the roof of the Museum, we only go south to get the card and then return to the Museum. We are NOT going north/east of the roof. Thanks to this, the Mutant does not freak out and we continue the game with him until the laboratory. Of course, this excludes Slavsky's joining. However, it is an interesting alternative and quite not obvious. Not everyone knows about this option. Most players, if they can go somewhere, go there. In this case, the authors of the game allowed an alternative fate for not visiting the entire roof. Cheers, maybe this knowledge will be useful to someone :)