Thinking out loud now.
Are they together in Mexico? IMO, it'd be easier to spot them if they're together. I've seen some cases where the suspect gets too comfortable partying down there and gets caught in some cantina. Does Daniel speak Spanish?
For all we know, Daniel could be in Los Angeles. They could be anyplace! Really, I don't know how LE does it, but they do.
It might help that Janith has some easy to spot tattoos. But gee, she sure has managed to get "lost".
The general public only has one picture that has been released of Daniel Flores. No mention of how tall he is or if he has any distinguishing tattoos, or may wear big black glasses sometimes. Nothing about him on on the local news lately. That's why I think LE must be tracking him down in other ways, and maybe in other locales.