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DNA testing is key in rape charges against Dedham man

A Dedham man pleaded not guilty Monday to raping and robbing two women in Boston in 2004, in a case that was revived after cutting-edge DNA testing allegedly ruled out his identical twin brother as a suspect.

Dwayne McNair , 33, was arrested and charged in 2012 for raping and robbing a woman in the Forest Hills area and, nine days later, raping and robbing another woman in Roxbury, the Suffolk district attorney’s office said in a statement.

Detectives used a condom retrieved from the scene by the victim in the latter incident to originally implicate McNair, prosecutors said. However, standard DNA testing could not differentiate McNair’s DNA from his brother’s.


Prosecutors temporarily withdrew their case in April to pursue newly developed DNA testing, announced late last year. That testing was able to differentiate between McNair and his identical twin brother, prosecutors said.

Results received on Sept. 5 from the new process, known as second-generation genome mapping, revealed that “Dwayne McNair was 2 billion times more likely to have been the source of the DNA evidence than his brother,” prosecutors said.

“The forensic application of this testing is new, and to the best of our knowledge our case will be the first prosecution to use it,” District Attorney Daniel F. Conley said in the statement. “The scientific foundation, on the other hand, is well-understood and widely-accepted.”

McNair was arraigned in Suffolk Superior Court on eight counts of aggravated rape, and two counts of armed robbery, for the two separate attacks in September 2004.

McNair was ordered held on $500,000 bail, and is due back in court Oct. 29.

McNair’s alleged accomplice, Anwar Thomas, 32, pleaded guilty in both attacks and is serving a lengthy prison sentence, prosecutors said.

More coverage:

Rape suspect indicted with cutting-edge DNA testing

Trisha Thadani can be reached at trisha.thadani@globe.com. Follow her on Twitter @TrishaThadani.