While the officer in the video states that the case will be regarded as a criminal threats investigation, the rumors flying have most people regarding this case as one of assault.
There are quite a few rumors going around on the internet already in regards to what Chris Brown actually did to Rihanna and the possible causes for the disturbance.
Some have speculated that Chris Brown is or was on some form of steroids, leaving him with the predisposition towards abusive anger. Others are now speculating that he assaulted Rihanna after supposedly learning that she gave him herpes.
Of course, all rumors are unfounded.