Usage patterns
〈人〉に死刑を宣告するto sentence someone to death
The court sentenced the defendant to death.
死刑を求刑するfor the prosecution to demand the death penalty
The prosecution demanded the death penalty.
死刑が確定するfor a death sentence to become final
The Supreme Court's ruling finalized the death sentence.
死刑になるto end up receiving the death penalty (informal)
If you do something like that, you might end up getting the death penalty.