MEXICO CITY—One day after Mexico angered U.S. officials by publishing an entire 751-page U.S. case file against former Defense Secretary Salvador Cienfuegos, the Mexican prosecutors who exonerated him released their own version—but with so many pages wholly blacked out it was almost impossible to tell what they’d found. The report released Jan. 17 by the Mexican Attorney General’s Office included a 226-page stretch with every page blacked out, followed by a 275-page stretch of blacked-out pages. In the few sections with less redacting, all names and images were blacked out. The officials appeared to be struggling to control the damage to the reputation of the justice system after prosecutors took just five days to completely absolve the retired general of U.S. allegations, backed by years of investigation, that he aided drug traffickers in return for bribes. President Andrés Manuel López Obrador on Jan. 16 dismissed the U.S. case as “fabricated” …