Strib, here, carrying a NY Times item.
An alternative explanation, Mueller refers things now from the Special Prosecution team to one of the NY U.S. Attorneys (likely the Southern District - SDNY), with all presently existing files and records farmed out in such a way, along with use immunity on testimony Weber or Podesta might be compelled to provide in the Manafort trial.
Segregating out all of the independently attained prior evidence, before any testimonial use immunity would apply, would be a clean approach to laying the groundwork for compelled immune testimony.
With clearly delineated separate independently obtained prior knowledge defined via the prosecuting jurisdictional decision, (the Ukraine based effort of Podesta and Weber, (as Manofort support cohorts in lobbying without reporting/disclosure of representation of a foreign nation), can be subsequently prosecuted based on the prior evidence, apart from any compelled testimony at the Manafort trial.
For now, only Manafort is on trial, Weber and Podesta may be on trial later; or they may cut a plea deal.
We shall see.
What readers need to understand: Use immunity for compelled testimony means the testimony or any "fruit of the poisoned tree" would be inadmissible in trying the immune individuals, but prior independently attained evidence is not excluded - it not being "fruit of the tainted tree." It is a way the government and judges have eaten away at the absolute sounding Bill of Rights language against compelled self-incrimination.