WATCH: DNA From Genealogy Websites Helps Track Down Suspect In Series Of Rapes

MONTGOMERY COUNTY – Montgomery County Cold Case Detectives arrested a suspect in connection with a series of rapes on Thursday, according to a Montgomery County Police Department press release.

Marlon Michael Alexander, 39, of Dairymaid Drive in Germantown was arrested for attempting to commit a sexual offense and for committing three, first-degree rapes in the Gaithersburg and Germantown areas between 2007 and 2011, the release stated. He has also been charged with first-degree burglary in the previously mentioned offenses as he broke into the victims’ homes before sexually assaulting them.

Police Chief Tom Manger said DNA was found in each case, but they didn’t know whose it was. In 2017, they sent the DNA from the cold cases to a company that has a database of DNA profiles from genealogy websites. The company used the database to find two people with a DNA connection to the unknown suspect. Police took those names, according to Manager, and used them to eventually track down Alexander.

Montgomery County Police lists the following incidents in which Alexander was charged with:

  • On August 11, 2007, at approximately 1:00 a..m., the suspect gained entry into the 25-year-old woman’s home located in the 18200 block of Lost Knife Circle in Gaithersburg and threatened the victim that he would shoot her if she did not perform a sexual act.  A struggle ensued and the suspect fled from the residence.  The suspect’s DNA was recovered in this case.


  • On June 19, 2010, at approximately 3:20 a.m., the suspect gained entry into the 68-year-old woman’s home located in the 20300 block of Beaconfield Terrace in Germantown.  He held an unknown weapon to the victim’s head and raped her. The suspect’s DNA evidence was recovered in this case.


  • On August 21, 2010, at approximately 4:15 a.m., the suspect forced entry into the 86-year-old woman’s home (Churchill Senior Living Center) located in the 21000 block of Father Hurley Boulevard in Germantown.  He was armed with a pair of scissors as he raped the victim.  The suspect struck the victim with his hands multiple times before he fled.  The suspect’s DNA recovered in this case was identified as belonging to the same suspect responsible for the August 11, 2007, and June 19, 2010 assaults.
  • On January 5, 2011, at approximately 12:45 a.m., the victim of the June 19, 2010, rape was victimized again in her home (located in the 20300 block of Beaconfield Terrace).  The suspect’s DNA left at the scene matched the DNA left at the three other crime scenes.

Alexander is being held without bond. Detectives believe that Alexander may have possibly committed additional sexual assaults and continue to examine similar cold case rapes in the county.

Copyright 2018 by All Rights Reserved. Montgomery County Police Department (Photo: Montgomery County Police Department)

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