You need to know your rights under renting. If you go to Cleveland's web-site there is a link about renting and your rights. Your landlord needs to give you a 24 hour notice if he/she is entering your house. If there is not a notice then he/she is violating the law.
You need to contact Cleveland Heights and ask them what you can do. The web link I mentioned can only take complaints from Cleveland proper residents.
Hope this helps and gets your landlord on the right track

1stlady,

If you have evidence of an unauthorized intruder our recommendation is to report it to the police ASAP and consider rekeying your doors.

After the fact..........consider notifying your landlord in witing with a copy of the police report. This approcah should serve to protect your interests, both if it is the landlord and if it is not. In any event, they should get the message that you are not going to tolerate this violation of privacy.