Finding out who my Dad's life insurance policy was through

Hi I'm Elaine and my step father (who raised me and was the only Dad I had) just passed away and I was the beneficiary growing up on my Dad's life insurance but after I became older me and my dad never talked about this anymore. My dad got cancer and died 2 weeks ago and I have no idea what insurance company he had his policy through and since I wasnt "biologically" his daughter I was not the next of kin but I was still more than likely the beneficiary because my dad only had me and no other children. How would I go about findind out if he still had life insurance and also how would I go about filing my claim>?