Can the police access my WhatsApp (even after I delete messages?)

If the police gain access to the contents of your phone, either because you have provided the password or through their forensic software, they can retrieve WhatsApp messages. In some cases, they may also be able to recover deleted messages, but this depends on factors such as how long ago they were deleted, how the phone has been used since, and how much time has passed since the deletion of data before the police seized the device. The more the phone has been used after deletion and the more time that has elapsed since the deletion, the lower the chances of full recovery.