"He was expected to side with prosecutors more often than O'Connor, although as an appeals court judge, his record in death penalty cases was mixed."
Maybe his Catholicism came into play. The AP seems to be trying to make this non-story a story.
Catholicism does not forbid capital punishment (BTW the current pope never said anything against the death penalty) and Alito has enforced the death penalty.
This really is not a "Catholic Position". Roman Catholics may support the death penalty; the Vatican had one up until 1968. Many bishops try to weave the "Seamless Garment" which nicely covers those who try to put abortion and the death penalty on the same moral plane. They are not and have never been; Thomas Aquinas writes on the subject.