Ship's Ballast

A jewelry salon in Seattle must move. They seek help everyplace. They ask the police for a little of their time to review their plan. Inspector Strong is given the job. The Chief trusts no one else.
At the salon he finds they have started a move plan. He has them destroy all but one copy and start a plan that tell them how to build the move plan. The owner sees the wisdom and uses the Inspector’s ideas. The Inspector helps build the planning manual but never sees the master move plan.
A month later the salon is robbed, but they get nothing. They tried to take the containers with the gems in them, but two men could not lift them. The salon’s hired security force for the move kills all three of the robbers. The police arrive but all is under control.
They continue the move to the new location and the police guard both the salon and their new location. There are no leads for the homicide division to follow up on
With no clear leads they decide to obtain a court order to inspect the containers at their new location. The security forces are all ex-military. Everyone is concerned if they choose to ignore the court order. The FBI has another problem on their plate but cannot discuss it with the local people. Other federal agencies know of the situation. To serve the order, everyone is outfitted in military combat material.
The security force at the new location has no problem with the court order and search. The search finds only the gems and extra weight in each container. The weight is some old ship ballast. Thus, making it almost impossible for several men to move.
The total gems are not worth the risk, no less when the shipments are split into four units. Where is the value for the risk? What situation is the federal agencies worried about in this attempted robbery and is that the value?