Red wax on a door lock can seem suspicious, but there is no universal evidence that it is a code used by burglars.
It could have a harmless explanation, though repeated or unexplained markings are worth documenting and checking.
Inspect the lock and surrounding doors for signs of tampering, and consider improving lighting, locks, or security cameras.
If you notice actual attempted entry or other suspicious activity, contact local law enforcement rather than assuming what the wax means…See below
