Does he use the t often? If so, chances are he tried to make it, then missed it. Either way, there should be footage of him at the t station. Does he use uber? If so, are there records of an uber driver picking someone up in the area he was last seen? Falling in the river is very unlikely. The walk from station square to the north side is over one bridge or another. However, no matter how drunk you are it very unlikely that you would fall over those railings. They're too high. Especially for his height. Check the t station cameras, then check uber records if possible.