If an accused murdered a witness, should he be deemed to have forfeited the right under the Sixth Amendment "to be confronted with" the witness, absent proof that the accused committed the murder for the purpose of rendering her unavailable as a witness?
Friedman, Richard D. "Does an Accused Forfeit the Confrontation Right by Murdering a Witness, Absent a Purpose to Render Her Unavailable?" Preview U. S. Sup. Ct. Cas. 35, no. 7 (2008): 364-8.