I would have gotten involved, If her life was in danger, being a good witness wouldn't do her any good if she died.
I have gotten involved before, and haven't regretted it in the least.
The thugs that did this need to pay with more than time in jail. The people that taped it also need to be charged as co defendants. I would call them animals. But that is disrespectful to animals. Hopefully they will get gang raped in prison then taken out like Jeffrey Dahmer.
But it's in California, They will probably get out in a year or less.