Sister takes keys to vandalize ex bf property

[Jose Quinones]

I am a landlord of a 4 unit building where I rent one unit to my sisters ex boyfriend/baby daddy. I keep the property keys on the key holder on the wall. My sister took the ex boyfriend spare key off my key ring without permission and vandalized his things. How can this affect me and what’s should I do? 

Obviously the bf, my tenant, feels as if I was involved and expects some sort resolution however, I told him thatin a sense I too am a victim of B&E as she didn’t have my consent to the keys.

I will be changing the locks and apologizing for the trouble but I feel that is all I am required to do, right? He needs to deal with the authorities and my sister. She shouldn’t habe taken the keys from my house without permission. 

[Nathan Gesner]

Quote from @Jose Quinones:

Pretend this wasn't your sister. Some complete stranger stole the keys, illegally entered a man's apartment, and vandalized his belongings.

I would apologize to the Tenant, change the locks immediately, change your process so this could never happen again, and then offer to assist the Tenant with filing a criminal complaint against the offender.

You shouldn't treat it any different just because she's family.