peter kelly and a friend were fishing on the minnesota side of the st croix river on tuesday when they heard three rowdy men across the water .
they asked them to be quiet and an argument ensued for three hours .
the three men asked kelly and his friend to come over so they drove to the wisconsin side , where a fight unfolded and kelly was fatally stabbed .
kelly , who volunteered as a high school wrestling coach in his spare time , leaves behind a wife and five children , all under the age of nine .