This is another good point: you can be interrogating (or interviewing) a suspect under investigation, use a withholding technique and successfully catch them in a lie, only to have them lying for a completely unrelated reason to the original inquiry. From what I've gathered, the best lies under interrogation are the ones with the most components of the truth and minimal superfluous information. The police will do everything to get you to talk and keep talking, which is why legal representation is so key.