Looking at the damage, there was clearly a substantial speed differential between the cyclist and his killer. Considering the narrow passage between the road furniture and the substandardly narrow bike lane and the fact that the crash occurred immediately prior to a signalized T-intersection (the reason for the road furniture: traffic calming), it's pretty hard to not think this is gross negligence on the part of the deputy.
Unfortunately, the LA Sheriff's department does not have video in their units. Even worse, they are apparently conducting the investigation themselves rather than bringing in the CHP, which creates a clear conflict of interest. Their track record speaks for itself, with eighteen of them indicted today.
http://www.foxnews.com/us/2013/12/09...investigation/
I suspect we will never know what actually happened, although we will get a fully spun account from the killer's colleagues that will be the official accounting until the victim's family's lawyers get busy.