New DNA testing aid for twin cases

Prosecutors in Boston were forced to put a rape suspect on trial three times before jurors were willing to convict him a decade ago. It wasn’t because of a lack of evidence, but because the suspect was an identical twin.

Similar cases have illustrated the challenges of prosecuting a twin. Because identical twins come from a single fertilised egg, standard DNA testing has not been able to differentiate between them.

But Boston prosecutors who have struggled with such cases believe they have a new tool to persuade jurors: cutting-edge DNA testing they say can distinguish between identical twins.

“The science behind this testing has been used in research, in paternity tests and in a variety of other capacities,” said Jake Wark, a spokesman for Suffolk District Attorney Daniel Conley, whose office is now prosecuting Dwayne McNair, a twin who is charged in the rapes and robberies of two women in 2004.

McNair was scheduled to go on trial last April. But after prosecutors heard about the new DNA test done by a German company, Eurofins Scientific, they temporarily withdrew the charges against McNair so they could get a new round of testing done on DNA taken from a condom. Eurofins says it has been able to identify genetic mutations to differentiate between twins.

Prosecutors re-indicted McNair earlier this month after the new test results pointed to McNair and ruled out his twin brother, Wark said.

Boston prosecutors have been through this before. In 2004 and 2005, two different juries were unable to reach verdicts in a rape case against another twin, Darrin Fernandez. Several jurors later said they could not reach unanimous verdicts because DNA found on the victim’s pillowcase could have come either Fernandez or his twin brother. Fernandez was convicted after a third trial.

Authorities in other states have also struggled with prosecuting twins in cases involving DNA evidence.

In Colorado, a former Army officer blamed his twin brother for a string of sexual assaults on young girls.

Investigators said DNA linked Aaron Lucas to the abduction of an 8-year-old girl in Colorado Springs and to other cases. Lucas’s twin denied involvement, and Lucas ended up pleading guilty in November in nine cases ranging from indecent exposure to kidnapping and rape. He was sentenced to 20 years to life in prison.

After the new DNA tests were conducted in the McNair case, prosecutors said the results showed McNair was 2 billion times more likely to have been the source of the DNA evidence than his twin.

McNair’s lawyer, Robert Tobin, said he will challenge the prosecution’s attempt to put it before a jury.