Don't forget that Kruger was also HIV positive, and messages and images on his phone were described by police as "shocking" and while police didn't name Davis, it appears the content backs up Davis' claim of some sort of self-defense - where Kruger was forcing him to engage in sexual activity of a type he did not want to do, and potentially by voice.

Use of lethal force is justified when one is in imminent fear of death, great bodily harm, kidnapping, or sexual assault.