According to his daughter, he converted at the end of his life, perhaps afraid of going to hell, but I don't know if he really regretted it because he never wanted to confess his crimes.
https://en.m.wikipedia.org/wiki/Hermann_Heuvers

Well, there's no sin that's greater than Our Lord's Redemption.  In a sense, the greater the crimes, the greater the glory Our Lord's Redemption and mercy.  He could have wiped away all of Stalin's atrocities with a single good Confession (including purpose of amendment).

I did catch this part:

Ishii was later granted immunity in the International Military Tribunal for the Far East by the United States government in exchange for information and research for the U.S. biological warfare program.
...
Although the Soviet authorities wished the prosecutions to take place, the United States objected after the reports of a team of military microbiologists headed by Lieutenant Colonel Murray Sanders stated that the information was "absolutely invaluable”; it "could never have been obtained in the United States because of scruples attached to experiments on humans" and "the information was obtained fairly cheaply."

Talk about a euphemism ("scruples") used to condone crimes against humanity.

According to his daughter, he converted at the end of his life, perhaps afraid of going to hell, but I don't know if he really regretted it because he never wanted to confess his crimes.
https://en.m.wikipedia.org/wiki/Hermann_Heuvers

If you're correct, and he wasn't truly sorry, then he didn't have proper dispositions. You think God is going to be out-smarted by a non repentant sinner, and "sneak" into heaven, even after a long Purgatory?

God is way more just than you will ever CONCEIVE of being. Just remember that. He's also smarter than you. (Did I mention I love understatements?) If you can see through this man and his possibly false (fear-motivated) repentance -- don't you think God would see through it as well?

This might sound strange, but your severe trial right now is a temptation to PRIDE of all things. It's a cloaked species of pride, even though it might not seem like it at first glance. You're being tempted to place your own righteousness, indignation, justice, etc. over the many perfections of the infinite God.

If you're correct, and he wasn't truly sorry, then he didn't have proper dispositions. You think God is going to be out-smarted by a non repentant sinner, and "sneak" into heaven, even after a long Purgatory?

If the man received the Sacrament of Baptism without the proper dispositions, then that would simply add to his punishment.  If he received it with the proper dispositions AND received the grace of final perseverance, then I would find it an edifying testimony to the great mercy of God.  We sinners find inspiration in the stories of great sinners who converted, St. Augustine, St. Mary of Egypt, St. Mary Magdalene, etc.

We know that one drop of Our Lord's Precious Blood suffices to wipe away all the sins of humanity .... If you combined the mass murders perpetrated by Mao, Stalin, Lenin, and every serial killer who ever lived and every individual murderer, every serial adulterer, fornicator, sodomite, every torturer, every thief and criminal, undoubtedly trillions and probably quadrillions of mortal sins, one drop of Our Lord's Precious Blood wipes it all away.

If you're correct, and he wasn't truly sorry, then he didn't have proper dispositions

.

If he was a pagan, then he had no obligation to confess any of the sins he committed before his baptism anyway. That sounds more to me like what happened.