There should be several criminals, and they should be planned in detail in advance, because this series of complex crimes is difficult to be completed by one person in such a short time.
The suspect should have all the keys of the bank and may know the money delivered by the bank in advance.
3. Check the other two people who have the key to the safe, others who know that the money has been transferred, and those who have the key to the bank. According to the clues provided by Yimou, they went to the local area to ask the witnesses who escaped from the criminals and took surveillance videos of nearby intersections. Check the hair left at the crime scene.