"Jeffie had caught the FBI red handed making payoffs with counterfeit money and needed to keep some as evidence."
You should be an attorney.
Thats good, real good!
So he stored the "evidence " in the freezer because he knew those SOB's would storm down the door and look everywhere to Steal" the evidence to protect themselves.
The sealing of the boxes is furthur "proof" that they don't want the evidence to see the light of day because they know it will incriminate the FBI, not WJ, who was going to disclose the evidence at the appropriate time anyway.