I did not have enough evidence to punish the user since you may have shot him or threatend him. Therefore, I added BryceMoore on Steam and asked for his side of the story. He said he tried to shoot around your feet but ended up shooting you, came back and killed you after some time. The user admitted to RDM and will be punished for it.
A tip is to use some sort of recording program to help cases like these as screenshots might not be enough.