These were not crimes committed inside the prisons, they were all committed against people OUTSIDE of the prisons walls by inmates serving life sentences/or on death row - held in solitary confinement .  This proves that the state does not have "the ability" the Church claims/assumes it has.  

The Church is mistaken, and She doesn't care.  I know that for a fact the U.S. bishops don't care about what this "three-year, $5 million, local, state and federal investigation" proved which took place in Santa Rosa, CA at Pelican Bay State Prison and published in the newspaper some 6 years after the Church changed Her historical position on capital punishment.