If there is suspicion that the kidnapping crosses into multiple States, or foreign nations, it becomes a federal crime, thus involving the FBI.
To state the obvious, proximity alone brings Mexico into the picture, compounded by the surveillance images, and the very nature of the crime, kidnapping being a fave among border gangsters.
No suspicion necessary after 24 hours - there’s a legal presumption that if they are held more than 24 hours they’ve been taken across a state line. Feds can invite themselves in even before the 24 hours has run.
18 U.S.C. Sec. 1201(b): “With respect to subsection (a)(1), above, the failure to release the victim within twenty-four hours after he shall have been unlawfully seized, confined, inveigled, decoyed, kidnapped, abducted, or carried away shall create a rebuttable presumption that such person has been transported in interstate or foreign commerce. Notwithstanding the preceding sentence, the fact that the presumption under this section has not yet taken effect does not preclude a Federal investigation of a possible violation of this section before the 24-hour period has ended.”