The thief in "Double Point Museum" is a very troublesome special NPC in the game. There are many ways to stop thieves from stealing. The first is to monitor exits. The thief must find a way to escape, so if you have a security officer responsible for monitoring all possible exits, they are unlikely to escape without encountering the security officer.
How to stop thieves in the Double Point Museum
Even the best security personnel cannot appear everywhere at the same time, so it is very important to have an effective strategy to stop crimes as much as possible.
Monitoring Exits
Thieves have to find ways to escape, so if you have a security officer responsible for monitoring all possible exits, they are unlikely to escape without encountering security officers. Security personnel can also notice their disguise when the thieves enter, thus preventing them from being caught before taking any action.
Camera cannot catch criminals
Camera has its purpose – especially when a crime occurs, it can remind security personnel and deter criminals, but capturing criminals through cameras alone does not prevent them from committing a crime. The nearest available guards will try to catch them when criminals are photographed by cameras, but they don't always succeed.
When you receive a reminder that the criminal is found, pause the game and open the employee menu. Find the guards who are chasing the criminals and move them manually to the criminals. This ensures you catch the criminal!
You can also hire a new guard directly and place them in the position of a potential thief.
Crime Guild
Sometimes, museums are attacked by Crime Guild, an organized robbery of about three criminals. Each guard can only deal with one criminal at a time, so make sure you have enough staff to deal with the entire criminal gang.
Golden moles can appear anywhere through the holes they dug in the ground and will escape through the same hole they enter.
The swamp people enter and exit through the toilet. If your museum has multiple toilets, they may attack from one or more toilets at the same time.
Giant marketing companies are common disruptors, but they usually move in groups to try to overwhelm your security power.
It is very important that the guards never reassign the captured criminals until they are finished escorting them out of the museum. If a caught criminal is not escorted by a guard, they will immediately try to retrieve the exhibits they stolen and continue their robbery plan unless they are caught again.