A White Bear Lake man pleaded guilty Monday to fatally stabbing a family friend last year.

Joseph J. Derks, 22, pleaded guilty in Ramsey County District Court to first-degree manslaughter in the Aug. 6 death of Robert D. Olson.

Derks was originally charged with second-degree murder without intent. He faces at least 8½ years in prison when he is sentenced on May 10. Prosecutors are expected to argue for a prison term of about 9½ years.

According to the criminal complaint: Derks stabbed Olson, 47, inside a home belonging to Derks' father in the 2500 block of Crown Hill Court.

Derks' 17-year-old brother had called him so the two could remove Olson from the home. Derks took a knife into the house when he arrived, went into the basement and saw Olson choking Derks' brother.

Others also saw the choking.

Derks told police that he stabbed Olson in the back and neck because Olson wouldn't stop choking his brother. Derks also accidentally stabbed his brother in the leg.