(CNN) A jury in Dallas County sentenced the father of a 3-year-old girl whose body was found in a culvert to life in prison, the Dallas district attorney announced on Wednesday.

Sherin Mathews ' body was found in October 2017, two weeks after her adoptive father, Wesley Mathews, 39, reported her missing.

On Monday, Mathews pleaded guilty to a charge of intentionally and knowingly causing serious bodily injury to a child. On Tuesday, he took the stand himself and spoke about the circumstances of her death, which had remained a mystery since her disappearance.

"Sherin's little body was so badly decomposed, due to the actions of this defendant, the medical examiner could not determine an official cause of death, which could have dramatically changed the way we were able to prosecute this case," lead prosecutor Jason Fine told jurors.

In 2017, Mathews originally said Sherin disappeared in the middle of the night, after he disciplined her outside their home for not drinking her milk.

Read More