Suspect in ‘Potomac River Rapist’ cold case arrested Genealogy websites and a cheek swab enabled U.S. Marshals to arrest a man suspected of being the “Potomac River Rapist,” who terrorized the nation’s capital in the 1990s

CONWAY, S.C. -- Genealogy websites and a cheek swab enabled U.S. Marshals to arrest a man suspected of being the “Potomac River Rapist,” who terrorized the nation’s capital in the 1990s.

News outlets report 60-year-old Giles Daniel Warrick is now awaiting extradition from Horry County, South Carolina. He’s accused of raping 10 women and killing one of them between 1991 and 1998 in Washington, D.C. and its surrounding suburbs.

Authorities said DNA evidence matched family profiles in genealogy services, enabling investigators to narrow their search after interviewing Warrick’s relatives.

“This man terrorized our community,” D.C. Police Chief Peter Newsham told The Washington Post.

Warrick had moved to South Carolina after working as a landscaper in Maryland. Police said detectives questioned him and obtained a cheek swab with his DNA to provide the match to crime scene evidence.

It’s unclear whether Warrick has a lawyer to speak for him.

Law enforcement officials had been looking for a suspect for years, trying to find an athletic man prone to throwing blankets or towels over his victims before starting to rape them, and making comments suggesting he had stalked them.

The victims included a teenage babysitter, a promising young scientist and women returning home from work or grocery shopping. Some were attacked in their homes with children inside.

Christine Mirzayan, a 28-year-old biochemist, was accosted in Georgetown in 1998 while walking home from a friend's cookout. She was dragged into a wooded area, sexually assaulted and bludgeoned to death with a 73-pound rock.

Her then-husband, David Hackos, told The Post that Warrick’s arrest “brings a huge relief” but also “brings us back to that time” of the killing.

In 2011, police and the FBI launched an ambitious public outreach campaign to find the Potomac River Rapist, so named because of the geographic area of the attacks. That effort included digital billboards, a $25,000 reward and podcasts and social media alerts aimed at soliciting tips, modeled after similar efforts that led to the arrest of former Boston mobster James "Whitey" Bulger.

But it took more recent developments in technology — and the advent of public genealogy services — to crack the case.

Sgt. Chris Homrock, who runs the Montgomery Police cold-case unit, said detectives submitted a genetic profile they had developed from crime scene evidence to a Virginia company, Parabon Nanolabs, which checked databases and identified a number of possible relatives of the suspect. Detectives interviewed them, learned of Warrick, and traveled to South Carolina to make the match.