A District man who pleaded guilty to killing his ex-girlfriend was sentenced to 18 years in prison Friday, authorities said.

Shawn Davis, 37, pleaded guilty to stabbing Tawanna Barnes-Copeland, 41, to death in December 2010.

Davis and Barnes-Copeland started a romantic relationship in the summer of 2010, according to the U.S. Attorney’s office. That ended after a few months, but when Barnes-Copeland suffered a leg injury at work, she called Davis and asked him to fill a prescription for pain medication, authorities said.

Davis went to her home the morning of Dec. 7, according to authorities, and after they argued he grabbed a kitchen knife and stabbed her more than 10 times.

Davis also attempted to make the death look like a burglary by taking Barnes-Copeland’s cellphone and pushing out a window screen, authorities said. He was arrested in early 2011.

Read more: The Post’s crime coverage