By Annie Potasznik | CBS11 NEWS |

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McKINNEY (CBSDFW.COM) – Son T. Nguyen, 71, of Richardson, was sentenced to 29 years in prison without parole by a jury that convicted him of sexually assaulting a 4-year-old girl.

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On Aug. 29, 2015, Nguyen sexually assaulted the child who was in his girlfriend’s care. When the little girl’s mother picked her up from the babysitter’s house in the evening, the girl immediately told her mother that her private part hurt. When asked why, the little girl described what Nguyen had done.

The girl’s mother immediately took her daughter to the pediatrician and soon thereafter to the REACH clinic for a sexual assault exam. Dr. Kristin Reeder conducted the medical exam and collected DNA evidence and clothing from the girl. DNA analysis results showed that Nguyen could not be excluded as a match for the DNA collected from the girl and her clothing.

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Plano Police Department Detective Danny Bryeans lead the criminal investigation. Days after the sexual assault, Lisa Martinez, from the Collin County Children’s Advocacy Center, conducted two forensic interviews with the girl during which she was able to describe what Nguyen had done to her.

The jury returned a guilty verdict for Aggravated Sexual Assault of a Child Under Six before sentencing Nguyen to 29 years in prison without parole.

The jury’s sentence means Nguyen will sit in prison until he’s 100 years old.

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