If the landlord opened a package addressed to you, then he very well may have committed a crime. If it was sent through the US Postal Service, you should contact the US Postal Inspector's office to see what should be done to press charges. If it was shipped through UPS or Fed Ex, or some other service you should contact your local authorities, or perhaps the FBI. Keep in mind, however, if you do pursue this, your lease will likely not be renewed.
Answered on Feb 11th, 2014 at 4:45 PM