A ridiculous fear pursued me, in fact: one could not die without having confessed all one’s lies. Not to God […] No, it was a matter of confessing to men […] Otherwise, were there but one lie hidden in a life, death made it definitive. No one, ever again, would know the truth on this point, since the only one to know it was precisely the dead man sleeping on his secret. That absolute murder of a truth used to make me dizzy. Today […] it would cause me, instead, subtle joys. The idea, for instance, that I am the only one to know what everyone is looking for and that I have at home an object which kept the police of three countries on the run is a sheer delight (4.21).
Part of the reason Jean-Baptiste is able to flip-flop like this – to go from despising the murder of a "truth" to loving it – is that he has come to a new realization of what "truth" is. In the world of his confession, "truth" isn’t the best way to see what’s really doing on. Instead, lies are preferable. The murder of a truth, then, is probably the best way to get someone to notice it – much the same way he omits pieces of his narrative so we’ll pay closer to attention to what’s missing, à la the Gospel of Luke and the omitted "seditious" cry of Jesus.