I don’t know the situation you are referring to. Can you explain?
The Ustasha, also called the “skull crushers” were a group made up of Catholics (and Muslims) who sought to exterminate the Orthodox Serbs and Jews from Croatia during World War II. The execuations were carried out largely by Catholic priests and friars. They had the support of Pope Pius. Their acts of brutality were so heinous that the Nazis spoke out against them.
You can find out a lot on the internet about this group. They are called by some “The worst killers in history”. Interestingly, most have never heard of them. This information has been scrubbed from our history books.