They can get that info quickly and routinely. From what I saw coming out of the Laundrie’s house when LE entered after Missing Persons was filed, the parents turned over a lot of access to personal stuff. Hard drives were in the mix there. Also when BL got warrant for arrest for,… well, bank fraud, they could pull stuff.
It’s not like the family is rolling in the money. I don’t think their finances so complex or hidden, yet I do not believe they kept large amounts under their floorboards.
I agree the Laundries finances aren't likely to be complex. And I've said before I don't think they are rolling in money. I don't know what of theirs was covered by the search warrant already executed and I don't know what LE took that belonged to them vs to Brian.
I don't agree that because their adult son was charged with a financial crime (it wasn't "bank fraud" per se) that gives the FBI the right to "pull stuff" related to the Laundries' finances. Might they do it anyway? Sure, the FBI has been known to go rogue and do things that couldn't be done without search warrants they didn't have and usually couldn't get. I hope that's not the case here but you never know.
JMO