I feel like when LE lies during questioning, it's usually because they have some evidence to point to a specific scenario and they want to try to get the person to admit to it by saying they have xyz, but maybe they don't. In doing that, the person could panic and admit to something because they think the police already know. I don't think they throw random things at the person to see what they say. Usually there is a reason for even the "lies" and it's because something points that the lie being somewhat true and they need the person being interviewed to fill in the pieces or conform what they think. So if LE said we know you had plans to meet up, but they really didn't, it could be just simply that in these cases when people are interacting with underage girls online there is usually a plan to lure them to a meet up. If LE thought that could be what was going on, they say to KAK I know there was a plan to meet up.. he thinks LE knows there was so he admits there was. LE lied because they didn't know for sure, but if KAK is admitting to it, then that could very well be what was happening.