In criminal cases, DNA is usually the prosecution’s smoking gun — except, of course, if there is an “evil twin.” In November, a judge in Colorado Springs ruled that a suspect, Army Lt. Aaron Lucas, should have the chance to blame his brother Brian for a string of sexual assaults because the DNA might be Brian’s. Brian hasn’t been charged and denies any involvement, but Aaron said Brian was in two crime-scene states that Aaron was never in. Said a Denver defense lawyer, “The only time I have seen [the evil-twin defense] was on ‘Law and Order: SVU.’ “