ROANOKE, Texas (CBSDFW.COM) – A former Northwest ISD middle school teacher and cheer coach in Roanoke will spend at least six years in prison for having sex with a student.

Katherine Harper, pleaded guilty on Thursday to sexual assault of a child and improper relationship between teacher and student.

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Katherine Harper

Harper was a teacher and coach at Tidwell Middle School.

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In December 2016, Trophy Club Police say they received information from Northwest ISD that Harper, then 27, had an improper relationship with a former student who was 15 years old at the time.

Police arrested Harper in March 2017.

This was her mug shot at the time.

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Katherine Harper – March 2017