DALLAS — In a Shakespearean twist, matching DNA pitted twin brothers against one another in a Houston rape trial Thursday.
At first it seemed like a tragic case that would present the usual tough challenges for prosecutors.
A 9-year-old girl was kidnapped off the streets of Houston on her way to school in October 2001 and raped in the back seat of a car.
Two men were arrested. Police say one of the men committed the rape, while the other drove the car. DNA was recovered at the crime scene.
But there was a problem: The two men are identical twins, so that means they have the same DNA. So what good is the DNA evidence?
The twin brothers are Aldo and Hugo Penaflor, now 23 years old. They are on trial this week in Houston. Both are charged with aggravated sexual assault and aggravated kidnapping.
But prosecutors have told the jury that Aldo Penaflor actually raped the young girl, while Hugo Penaflor was at the wheel of the car.
However, Aldo Penaflor’s lawyer told jurors in his opening argument that the DNA is "inconclusive" and raises "reasonable doubt" because the two suspects are identical twins and therefore share the exact same DNA.
In turn, Hugo Penaflor’s lawyer, Ted Doebbler said he's not certain the DNA will even matter because Aldo Penaflor confessed to police that he raped the girl. His 40-minute teary confession regarding the girl’s abduction and rape was shown to the jury on Thursday.
In the confession, Aldo Penaflor repeatedly said that he knew what he was doing was wrong and that he would “probably go to hell” for the crime.
"DNA is an issue only because they are twins," said Doebbler. "There's a confession from Aldo [Penaflor] that obviously puts him as the perpetrator."
Hugo Penaflor testified against his brother on Thursday as part of a plea deal. That combined with the taped confession by Aldo Penaflor could make the dispute over DNA irrelevant.
For his cooperation in the plea deal, Hugo Penaflor will get a maximum sentence of 15 years in prison.
One brother’s crime leads to arrest of the other
There is yet another twist in the story. The police didn't stumble onto the suspects for more than a year after the crime.
They got their break in the case when Hugo Penaflor was convicted of burglary in 2002 and his DNA was entered into the Texas statewide DNA database, revealing a match to evidence in the young girl’s rape.
So Hugo Penaflor’s DNA was used to help catch his identical twin brother, Aldo Penaflor, who now faces up to life in prison if he's convicted of raping the 9-year-old girl.
Jim Cummins is NBC News' Dallas bureau chief and lead correspondent.