Actually, not to get totally gross, but the stereotype of the very clever evasive sociopath -- serial killers in this instance -- seems to be really wrong. Gary Ridgway for example was hardly highly intelligent. But there's this social concept of them as being somewhere between Hannibal and Ted Bundy, when in reality they're mainly powered by nightmarish drives and irresistible urges, and conscious rational thought apparently counts for very little. (Like, see Trump bragging about how alpha male and what a great dealmaker and businessman he is -- and the moment he's flattered, he totally caves and not only gives away the farm but the farmhouse and the hatchery next door.)