A Small Follow-Up on the Death Penalty

In class, we have recently finished talking about the death penalty after having several mock-capital court cases. Going into this unit, I didn't have a particular stance on the death penalty but I leaned against it. After all of the debates, I feel that the death penalty is far too imperfect to be implemented in all cases. The death penalty is too arbitrary. There are too many factors to consider such as the manner of the crime committed and the possible non statutory mitigating factors. There is too much burden on the jury and on the potential executioners to have to sentence someone to be executed or execute someone. I think that all non-statutory mitigating factors should also be considered by the jury. In a capital case, a life is at stake, therefore a culmination of one's life should be considered.
I think the only humane way to execute someone is through lethal injection. I am shocked that other methods such as electrocution and gas chamber aren't considered cruel and unusual punishment. I understand that if the crime is bad enough, the offender should be punished more severely, but there has to be limits. The punishment should be death, not the unnecessary pain that may come with it.
I am still unsure whether an inmate on death row should be allowed to change his/her ways, like Clifford Boggess. I think that there is no way to tell if someone has actually changed and therefore, there is no way to give someone the chance to change.
I am against the death penalty now because I believe there are better solutions that an eye for an eye.