I realize this post is very old, so you may not see this, but William A Evans was my wife's brother. I have a great deal of information about him, his last mission and some of his other missions which I could share. Given the highly classified nature of his work in Special Forces some of the information is thin to this day, but the mission which resulted in his death played a pivotal role in the war, and the start of the infamous bombing missions in Cambodia. Write me if you would like to hear more or if you have gathered any information on your own about him. I would enjoy hearing about this.
Lee