Does home insurance cover stolen items from an unlocked apartment that I am co-renting?

First, why is the apartment unlocked? An unlocked apartment can look suspicious to an insurance company. Whether or not the apartment was unlocked, insurance companies are primarily interested in the police report. The police report will determine if there is any indication of fraud.

Second, your items may be covered at up to 10% of the personal property coverage on your home insurance policy. Example: if your home insurance covers personal property contents at $100,000, then you would have up to $10,000 for personal property at another residence. However, b/c this is a secondary residence your items may not be covered b/c you are expected to have a separate secondary insurance policy.