A 37-year-old Columbus man has pleaded guilty to attempted incest.

Authorities say the man's 31-year-old sister reported that he had drugged her with prescription sleeping pills and raped her.

His name is not being used in order to protect his sister's identity.

As part of an agreement with Platte County prosecutors, the man also pleaded no contest to a charge of making terroristic threats. In return, a charge of first-degree sexual assault was dropped.

Sentencing was set for April 18.

Columbus Police say they began an investigation in December when told that the man had threatened the woman and her son. She said the incident occurred last fall.