The Killer
If they lived, then great, if they died, so be it.
The friend did agree to be there at the killing, but refused to actually do anything untoward.
He really wanted to get back in the good graces of the band that fired him. He went from making lots of money and attending the best parties, to just being a hanger on. He knew the band wanted full control of their name. He knew there was a battle going on. He asked one of his friends to help him, but the friend said no. What did he need help with?
Confession
While making a documentary about famous musicians of the 20th century, producers interviewed a man who was very close to this permanent A+ list musician. They just wanted background on the life of the musician, but ended up getting told that the A+ list musician was murdered and he knew who did it. The musician's death has always been considered accidental, but apparently this man has some evidence to suggest otherwise and now the producers have switched to an entirely different documentary.