(AP) — Morgan Harrington's parents were so convinced that a serial offender was responsible for their daughter's killing in 2009, they started a nonprofit foundation aimed at protecting other young women. Five years later, the Harringtons are reacting with a mixture of both sadness and relief to the news that the arrest of a man in the recent disappearance of a University of Virginia student has provided a "forensic link" to their 20-year-old daughter's unsolved killing. Two years ago, the FBI said DNA evidence showed that Harrington's killer also was responsible for a 2005 rape in northern Virginia, so Matthew could be linked to that assault as well, although City of Fairfax police declined to comment, citing their ongoing investigation. The authorities seem to be working systematically to link Matthew's DNA to an expanding circle of attacks on women, Steve Benjamin, past president of the National Association of Criminal Defense Lawyers, suggested Tuesday. Between searches of Matthew's car and apartment and his arrest on a charge of abducting Graham last week, police had ample opportunity to obtain genetic evidence connecting him to multiple attacks, Benjamin said. Sept.