You can upload the image to a third party source, such as imgur.
You need to use this template:
[b]Staff Member(s) Name:[/b]
[b]Staff Member(s) SteamID:[/b]
[b]What did the Staff Member(s) do?:[/b]
[b]What server(s) was this on?:[/b]
[b]Evidence:[/b]
You could also install plays.tv or shadowplay and record your game. Because if you don't provide proof that there indeed wasn't a body there we will have to trust the staff member's word that there was.