For starters, who was at that party? Among all of them, they should be able to find at least one witness.
If it really went down as he claimed, then I think Tennen must have been an unwelcome guest at the party. If so, it was probably something he said.
Don't interpret my speculation as condoning what happened. Furthermore, someone should have intervened -- no matter how far out-of-line they thought Tennen might have been.
I’m wondering if he ever really was AT the Party.