Simple: it didn't happen.
If Terri dies in the next week, that's God's will too. It is also God's will to tally this grevious murder to the sin-account of those responsible. They are storing up wrath for themsleves against Judgment Day. Or perhaps they will turn to God later, greatly magnifying His grace shown to such heinous transgressors (and we, by the way, are no better in potential in our own black and wicked hearts). That's not for us to know.
What is for us to know: a Christian can only defend Terri, an innocent woman, and here's why: God's revealed will is "Thou shalt not kill" (Exo. 20:13). God is His OWN spokesperson in this case, and the commandment is very clear, black and white.
Soli Deo Gloria
Get serious. Most Christians understand that the state has the right, under God and without contravention of Ex 20:13, to administer the death penalty to, inter alia Scott Peterson. Moreover, most Christians understand that we have the right to use deadly force in a just war and in just law enforcement without contravention of Ex 20:13. [I believe that even phantasmagorical RCC dogma would allow that.]
So, the citation of Ex 20:13 (more properly translated "You shall not murder") begins the inquiry, it does not end it. Those who glibly cite Ex 20:13 for support of their political argument are really echoing unsupported RCC dogma, not the Scriptures.