RedactedNarrative: Subject and Victim arrived at Cedar Hill Marina, Dale Hollow, at approximately 9:30 am on 08/12/2015.  The drove out into the main channel and shut the engine down and began to drift.  They drifted several hours and intermittently jumped in the lake to cool off.  They drifted into Kyle Branch, and Victim jumped in by himself, without a PFD.  Once he jumped in, he was never seen again.  Subject thought he was joking around and thought he was under the boat or on the bank.  After approximately 20 minutes, Subject reported Victim missing.  Upon my arrival, Subject was still in his pontoon boat and was still in the cove at the approximate location of Victim''s last seen location.  Upon initial interview with Subject, he indicated there was no alcohol involved and that he was not sure of the exact location where Victim jumped into the water.  After several interviews, Subject stated there was alcohol involved, along with some type of pills (not sure of name of pills).