Self-inflicted?

Hmmm....
18 stab wounds and two slashes to the face.
Yeah, I suppose it's logical the guy just ran into the knife, over and over.

Story:
A medical examiner testified that Walker Sisk, who volunteered with the Seminole Trail Volunteer Fire Department, suffered 18 stab wounds and two slashes to the face.

During the trial, Andrew R. Alston brought in an aikido expert to show how the victim could have inflicted the stab wounds on himself during a struggle over a knife. Alston had taken aikido classes the summer before the killing, according to testimony.

Alston later testified he pulled a knife because he feared Sisk, and that he stabbed him in self-defense.

Source