The doctor was one of the few doctors who would abort babies who were far enough along in pregnancy that many would have survived if born at the point of the doctor-enforced death - essentially infanticide.
I'm as shamed of our culture for this barbaric act that is paraded as some advance in culture (though it was a barbaric practice throughout the ages and is in contradiction to science), but God reserves the rights to bring vengeance.
Anyone who takes a human life has taken something so valuable, they've forfeited their own. There is judgment awaiting those who are responsible for the deaths of the innocent, whether through manipulation of legal systems or taking the lives of the innocent and helpless young.
This is a mark of cultural shame and disgrace.
But vengeance is God's.
Attempting to take God's role, whether deciding how long innocents' lives last, or deciding how long the guilty live - both are attempting to take God's role - it is He who decides who lives and dies*. Lucifer started the trend of wanting to take God's place, and both the abortionists and the man who shot this guy are guilty of the same sin.
http://news.yahoo.com/s/ap/20090531/ap_on_re_us/us_tiller_shooting
*After the flood, God did enforce the death penalty, and while it's a much longer and different discussion, God doesn't seem to be in favor of anarchy and protecting the accused through trials requiring multiple witness' testimonies, etc.