It was a dark and stormy night...
No wait, no it wasn't! It was a clear sunny day. When Brian had 3 of his old buddies from school over for a get together in Texas. They were all aged 35.
His friends were named Louis, Gus (or "Augustine") and Diana. Brian didn't know it, but this would be his last day on the face of the Earth.
Brian did however know the history behind his friends. He knew which one of them was a murderer. He had for years. He only considerered the possibility of him getting killed last minute.
He wrote the following letter:
Dear whomever it may concern,
This is very important. It's become the centre of my attention that I could die on this very day, 8/6/2015. I am leaving this message in hopes to tell you who it is but in all the current emotions I can't remember his name.
I apologise if this doesn't work out, but I'm trying my best. Be sure to analyse this letter very carefully. Now just in case I will be travelling to a new world, goodbye.
Using all the given information in this puzzle, what is the most accurate guess at the murderer you can possibly make?