Wisconsin has dissected Zellner's court filing to determine evidence that was overlooked at the time Avery was convicted of killing Halbach. Zellner contends that the new battery of tests can be done within the next three months, if not sooner. She said the tests will reveal who killed Halbach and will show there was massive evidence planting — not only by Manitowoc County law enforcement, but also possibly by civilian searchers following Halbach's disappearance.
I would like ask about the backshifting in the passage in bold in the above excerpt. Can you explain to me why the backshifting is like that. If I applied my school knowledge concerning this matter, the clause would be: …She said the tests would reveal who had killed Halbach and would show there had been massive evidence planting — not only by Manitowoc County law enforcement, but also possibly by civilian searchers following Halbach's disappearance.