Chronic liars are unbelievable. As you point out, they will say anything at anytime to anybody even when a blind man could see that it's a lie.
A few years back one of those idiots attempted to convince me that he had been in the same small room with me the day before attending a one-time-only presentation. He went so far as to name the fellow who was sitting on his right. The fellow he named was present and he was sitting directly in front of me, but he had no one sitting in the same row on either side of him. I was in the back row and had a clear view of everyone in the room, including those who arrived late or skipped out a bit early. I had been looking for this guy for two days as he was the one who needed to show up at my motel to pay for my room before I checked out the next morning.