Okay, what about spoonfeeding the records? If they got access to part 1/N, why did that not entail full access to the data? Otherwise they wouldn’t even be able to chunk it in the first place, no?
Just a guess. If the facts explained in those records prescribe after four years, agents must be tempted to release the part N/N in four years and a day. Without knowing the full history any demand could be dismissed.
Not different than nuclear companies adamantly repeating for the first years that no one was killed by a nuclear accident.
Also they didn't get access to part 1/n. They got access to part 1/?. And then 2/?. And then 3/?.