Via the Washington Post’s Crime Scene blog, word that Prince William and Fairfax police say they have DNA evidence that connects the Halloween rapes of two teenage girls in Dale City to an alleged serial rapist who is suspected in at least a dozen other sexual assaults up and down the East Coast. The rapes span from 1997 to this year, with “at least four rapes in Fairfax County between 1999 and 2001, several in…