Tsarnaev is going to die in prison. We’ve known that since he made it out of that boat alive. Whether that death is the result of lethal injection, old age, or a shard of glass is all thats left to decide. The prosecution is still attempting to have the state give itself permission to kill him, while the defense is attempting make sure the state does not give itself that permission. But no one in that court is vying for any result other than Dzhokhar Tsarnaev living out the rest of his life behind bars.
And keep in mind that the death penalty will not happen soon. It will be after a long process of appeals and red tape that will go on for years¹. It will not be a cathartic vengeful act at high noon at the marathon finish line. It will be (if his fellow inmates don’t preempt the states action) a dreary, long debated act of state killing in something like the year 2030.
The prosecution is currently arguing that his crimes are so severe that the death penalty is appropriate. The defense is arguing that that his older brother held enough influence that it moderates Dzhokhar’s culpability enough to withhold the death penalty. What we are debating is how many decades he will rot before he dies, and who has permission to kill him. There is not massive separation between the possible outcomes. And no one is saying he should ever spend another day outside of prison.
Tsarnaev will live the rest of his life in a cage, the court is just figuring out the details.