I traveled to the fjords and came back to Broken Valley. As I approached the great walkway leading up to the temple I thought about that third slayer whom I was never certain was killed or not. Amazingly I recalled the area where I thought I last saw him while I was in hectic mortal combat with the other two slayers and I traveled to that area which happened to be the lower ramp to the left of the main walkway leading to the temple. Suddenly the slayer just appeared right in front of me and began casting spells on himself then lunged into me with his sword. I took him down in a few quick strokes and heard Talana talking to me. I approached the temple door and the text changed from lockpicking to key. I happily entered the temple and passed through the Zandalor cutscene without difficulty.
Thanks Raze. It was your thought process that lead me to the answer.
