In the Pilot episode, titled The End, after Lister has woken from suspension he asks Holly how everyone died:
HOLLY: The drive plate was inefficiently repaired. It blew, and the
entire crew was subjected to a lethal dose of cadmium 2 before I could
seal the area.
And then, when he gets to the drive room and starts trying to identify the piles of dust by taste, it is said:
HOLLY: ... that's Second Technician Rimmer.
LISTER: Oh, yeah? I didn't recognise him without his report book. What
was Rimmer doing in the Drive Room?
HOLLY: He was explaining to the Captain why he hadn't sealed the drive
The clear implication being that, yes, Rimmer was responsible for the deaths of the crew of the Jupiter Mining Corporation's Red Dwarf.
What a smeg-head.