Who Killed Mr. Tibbles?

Mine and NAL's entry into GMC Jam 37 where the theme was "It Knows Something You Don't".

A heinous crime has been committed in Spuddie's Doll House.

Mr. Tibbles has been MURDERED in COLD BLOOD!

Spuddie saw the whole thing... but he's got a short attention span. Can you help him piece together the details of the crime?