You've met our trio of Vegas detectives.  A normal department would have this done in less than a day, but no surprises here that it's not a priority for the brothers.  My guess, is that there is something to the timeline difference idea between Vegas and Philly/South Dakota/New York story line.  Let's say its around the 9.29 date in Vegas to line up with most of what is going on in Twin Peaks, but only 9.21 date in South Dakota.  Our dynamic duo of Cole and Albert might not show up for another episode of 2 as they catch up with the date in Vegas (I'm pretty linear myself, so this idea is a bit our of my comfort zone, but I must admit it is possible at this point).

The FBI is ready to leave South Dakota and visit the coordinates. On rout they are going to want to stop in Vegas. Everything is lining up we are an episode or two away from Dale being picked up by his friends and his one finger is going to give Cole and Albert the clue of what is going on.

It has been two episodes, but it is questionable whether much time has past. It still seems to be 9/29, in Twin Peaks at least, since they are still planning their hike to Jack Rabbits Palace for two days hence.

I think that Dougie and Janey-E were taken into custody moments after they were interviewed, thus the prints were collected that day late afternoon. Dougie went to the Doctor's the next day and had happy arm flappy time with the missus the following night. Then he had his meeting with the Mitchums the day after. The timeline will likely go back to the Fuscos in episode 12 which will probably ping on the FBI's database not long after that.

Yay! Fellas, waitin anxiously for the Special Agent Dale Cooper Awakening. Hope the encounter brings up in him what is missing 🙂 Until then let's drink some more coffee!