This is a hard question, thanks for dealing with it thoughtfully. Though I have historically been anti-death penalty, and remain personally uncomfortable with it, I see the biblical case for it (and I hold the Bible as more authoritative than the institutional church or my personal feelings). The “imago Dei” point is precisely the grounds given for capital punishment:

“Whoever sheds the blood of man,

by man shall his blood be shed,

for God made man in his own image.”

—Genesis 9:6

But wherever one lands on the debate, it should be a solemn consideration. It’s really disturbing to see people displaying any kind of glee over state executions, even if justly rendered.