Can LE search unopened/locked containers in the vehicle after a positive alert/final indication?

Yes. It is well settled law that containers in a vehicle can be searched as long as the probable cause developed would indicate that the container could contain the contraband or evidence for which probable cause exists. In addition, “[a] passenger’s personal belongings, just like the driver’s belongings or containers attached to the car like a glove compartment, are “in” the car, and the officer has probable cause to search for contraband in the car.” (Emphasis in original). Wyoming v. Houghton (1999) 526 U.S. 295, 303. “The sensible rule (and the one supported by history and caselaw) is that such a package may be searched, whether or not its owner is present as a passenger or otherwise, because it may contain the contraband that the officer has reason to believe is in the car.” Wyoming v. Houghton, supra, at 307.