This I was not aware of but it makes sense:
It always creeped me out that Capote fell in love with Perry Smith, one of the murderers.
When these 2 dirtbags finally got their just desserts, Capote was much criticized by the congoscenti for not doing more to help them avoid the noose.
A rather good movie of the Clutter murders was made with Robert Blake portraying Smith. Blake, of course, went on to have a personal involvement with another killing, but for him, no noose.