Tenant damages or Contractor damages?

[Kyle Rice]

Ok I'm having a lot of issues with tenants saying that they don't know what happened regarding damage to units. For ex. I let the plumber in to fix a boiler and noticed that the steps from the garage to the house were destroyed. It appeared that they're been driven over with the tenants truck since there was a tire mark on the steps. The tenant stated that the steps just fell apart while they were stepping on them. I have no way of verifying this and it's possible that the steps were not installed correctly. Who would you hold responsible the tenant or the contractor that installed them? This type of scenario has happened more than once. How do you guys deal with this type of issue?