Wang Song has quite a workload; he has already questioned all the online specialty stores.
But as of now, no substantial clues have emerged.
According to Wang Song's analysis, when the robbers were purchasing the bomb-proof suits, they probably already considered that the police would trace the origins through online channels.
So even if they bought them online, it might be sent to another location and then transported to Binzhou City through some means.
If this is the only clue, then Wang Song must investigate from a national perspective to hunt for any traces.
Then there is offline purchasing.
No clues have emerged in this aspect yet.
There are some security companies in Binzhou City.
But these security companies would not equip their employees with bomb-proof suits that offer 100% protection.
