RedactedNarrative: V1 was drifting on the Missouri River and letting the current guide the boat. Victim stepped over the railing of the pontoon boat to urinate and fell into the water off the bow.  Operator advises that the victim was able to swim briefly but then went underwater.  Rescue personnel searched for the victim with side sonar but didn't ever locate the victim.  As of 9/1/2016, the victim has not been found.  The victim was not wearing a life jacket and had been drinking.  The Operator of the boat had also been drinking.