Is this corroborating evidence? I won't say definitively. The blood looks too red and I don't see a prominent wound, however the source is major news media so that would seriously reduce the probability of some wild-eyed right-wing blogger PhotoShopping a smoking gun item.
Here is the ABC news story and a video clip:
GPS locating on the photo verifies it comes from the scene and the date/time stamp indicate it was taken three minutes after the shooting. Sounds pretty valid at this point.