How do colleges figure out if you are lying or not

As a fan of The Americans, I can’t resist listing this one (quoted from a US News article) “In July 2010, Harvard University stripped Russian spy Andrey Bezrukov—who had attended Harvard under the name Donald H. Heathfield—of his graduate degree in public administration. “The Kennedy School usually severs its relationship with a student when it is discovered that the individual’s application contains inaccuracies,” the Harvard Crimson reported.”