Tammy's Dec 11th exhumation was not public knowledge until Dec 20th when LE released the first press release on facebook:
Rexburg Police Department
That said, we shouldn't forget that Chad previously worked in the Springville Cemetery and he grew up in Springville and went to HS there. The cemetery workers who had to dig up Tammy could have inadvertently alerted Chad to it happening. I'm not saying they were complicit in any plot, but someone who knew Chad could have sent Chad a text such as "Dude, why is Tammy being dug up?" Also, it's hard to keep things like this quiet in a small town. If local LE used their radios to coordinate the exhumation, then the activity might have been picked up by someone listening in with a ham radio or police scanner radio. And then that person could have passed the info on to Chad.
One thing to take into account is the time difference between Utah and Hawaii. Assuming Lori and Chad were in Kauai and hypothetically they got a text from some "concerned friend" on Dec 11 just after 6:30 AM in UT, saying they just dug Tammy up... It would be 3:30 AM in Hawaii:
Time Zone Converter – Time Difference Calculator
They might have been asleep when the message came through but they would theoretically have extra time to decide to get a morning flight back to AZ, contact someone in AZ with instructions, or send an overnight airmail package to Alex to arrive by the afternoon of Dec 12th.
MOO.