[Alberta's Child]

The official announcement was that Mueller turned the matter over to the Southern District of NY because it was outside Mueller's jurisdiction as special counsel.

Who knows if that's true ... but it seems like a reasonable explanation.

[Alas Babylon!]

Then why is Manafort’s dealings from 2006 part of his jurisdiction?

Manafort worked the Trump campaign for 3 months, mainly due to his expertise in ensuring there wasn’t going to be a floor fight at the GOP Convention over delegates. He did his thing, and then left the campaign.

Mueller’s actions regarding Manafort makes no sense.