For the sake of David's family, I hope that the defendants will for once try to do the right thing and admit their guilt. Putting his family through four trials is torture for them and the defendants should try to think of their own families too. Taking responsibility for their actions would be a start at rehabilitation (if there is such a thing with sociopaths). 
But then if they had any empathy they would never have killed David to begin with. 
My thoughts are with David's family and friends.