This is the ultimate question many Christians and non-believers alike arrive at sooner or later. It could also be phrased as follows:
As God is omnipotent, omniscient and knows everything in advance, why did He embark on the Adam & Eve creation mission at all...It doesn't look like 'Mission Accomplished' given the horrible consequences of sin throughout human history. Many very smart people tried to come up with all sorts of 'logical', humanly comprehensive solutions to address the big question: 'Why did God start creation and leave Satan around..'. Great brains wrote great books like 'Earth's earliest ages' from Pember. I find all of them contribute in some way or form to understanding 'The problem of pain' as C.S. Lewis defined the big problem.
Nevertheless, as we are human and bound by the very laws and limitations of our three dimensional space and linear time dimension, we will never fully understand. Hence, my answer to your contact's question is the only answer that satisfies me personally (and I have a Master's in science):
The Lord God, our Creator, did the most incredible of all by coming to Earth in the flesh, in the person of his Son Yeshua, to suffer the full and most dire, righteous consequences of the Sin, caused by Satan's delusion of Adam and Eve. The Lord punished Himself according to His eternal, righteous Law, for the sin committed by us. He truly suffered the deepest anguish in our place. Why did He do that?
It is Satan who in his power had the capacity to deceive us. We cannot make God responsible for that, although we struggle with the question: 'But if God knows everything in advance, why take the risk of creating it in the way He did'. We will never entirely understand. It's not our call. God's answer is that He provided the dearest He had as a sacrifice for us: his Son. This goes beyond our logic. This is Love of a divine degree - and it's free for all. Not something we can understand, but an offer we should not refuse and which we can enjoy through the Holy Spirit. If the Lord would have had an easier and different way to accomplish His Mission, I'm sure he would have chosen to. His ways are not ours though. Providing His Son in our place as the Messiah, is beyond human understanding, but a gift that hopefully your contact in prison will accept. He has suffered beyond understanding. He can stand beside us in our suffering. He entered our space. He's there, for prison inmates, and will show compassion for their deepest sorrows and doubts. May his Love overcome his/her reservations and open the door to His overwhelming love and spiritual healing.