Starting? Suspect?
Strange, considering all the images that were received from its recent find were showing beyond any doubt that the Kormoran had sunk it, and even some of the people who claimed sub involvement had retracted their claims.
I think we pretty well know what happened to Sydney; the images show that Kormoran's crew gave an accurate account. Sydney's bridge and virtually all gun stations were destroyed very quickly by Kormoran's fire, only one turret would finally inflict the fatal damage on the Kormoran. It's still a mystery why the lifeboats weren't launched, but they certainly never were - and were found on the bottom next to the ship.
I don't think there's any room for alternative theories at this point.