It's been speculated that police require a warrant to search passenger lists for the name of someone who isn't suspected of terrorism or wanted for a crime. They need probable cause, just as with any other kind of search of an apparently law-abiding citizen's bank accounts, phone records etc.Would the US Marshal need a confidential source to tell them as recent as this past week to check the passenger manifest for a ticket purchased as CA (i.e., defendant's sister)? I sure hope not! JMO
So first, they needed to supply probable cause to get a warrant to search the sister's belongings, to see whether her passport was there. They had to convince a judge that it was highly likely KA had flown out of the country on her sister's passport. Then, they had to get another warrant with probable cause that the passport had been used fraudently by KA.
None of this was urgent, in the sense that someone's life was at risk.
IMO, judges will want.to see evidence police have followed all avenues open to them for possible evidence, before granting a search warrant allowing them to go through all the sister's stuff.
JMO