A Northern Virginia man faces life in prison if convicted of a series of sexual assaults that occurred more than a decade ago. Police say he targeted students at two Washington-area universities. He was arrested because of new technology and the work of a special unit that worked with the U.S. attorney and others to close sexual assault cases.

Ernesto Ramon Mercado, 54, of Arlington, is charged with first- and second-degree sexual abuse in connection with a series of home invasion rapes. He is linked to a total of six attacks between 2008 and 2012.

“These cases stem from six unsolved rapes during home invasions,” said Metropolitan Police Department Chief Pamela Smith. “Five of these crimes occurred in the Georgetown area, Glover Park in northwest D.C. and one near the University of Maryland in College Park.”

Investigators say Mercado targeted young women living in off-campus housing, striking late at night or before dawn.

“In each case, Mercado likely identified his victims through stalking and peeping tom activity,” said MPD Detective Alexander Mac Bean.

Police said he sought out drunken victims, usually on the way home, and waited until the victim was asleep before breaking in or entering through an unlocked door.

The perpetrator became known as the “Georgetown Cuddler,” but the lead investigator in the case says that term belies the seriousness of the crimes he was accused of and the harm suffered by the victims.

“This man is a predator and his intention was not to cuddle these women, but to rape them,” Mac Bean said.

How DNA and genealogy helped police find the suspect

Police obtained DNA from the crime scene. Although they couldn't identify who it came from, they knew it came from the same person.

Court documents show police targeted Mercado using DNA profiles submitted to a consumer genealogy service. It is a research tool known as genetic genealogy. Police can search DNA profiles found at a crime scene to find people related to the suspect, narrowing the pool of potential perpetrators.

It is possible that a relative of Mercado created a family tree and police traced the branches as the case quickly intensified.

Police conducted surveillance on Mercado's Arlington home on Monday and obtained a search warrant for his DNA.

“We received this sample yesterday morning, submitted it for rapid DNA analysis – another tool that was only recently introduced – and had a DNA match by early afternoon,” said U.S. Attorney Matthew Graves.

“The reward of a case like this is being able to tell a victim years later that we have identified the perpetrator who committed this crime,” Mac Bean said.

When Mercado was arrested, time was of the essence. Investigators determined he may have been a rideshare driver. They considered the possibility that he might find more victims through this work.

Police hope that by releasing pictures of Mercado, anyone else who had an encounter with him will come forward.

Police believe Mercado is responsible for dozens of cases of sexual assault, burglary and voyeurism and that there may be other victims. Anyone who may have relevant information or who may have been the victim of a related attack is asked to contact police.