Did serial killer Jeffrey Dahmer take steps to put himself in prison to stop the killing as someone suggested to me?

This is a nice idea and a nice notion and in fact is a kind of misinterpretation of the sequence of events here. This is the intermixing of what happened in the timeline of events resulting in his arrest and the inner turmoil growing within him causing him to become more and more unhinged. That was his undoing, but it was not a lofty notion bringing it about and it was not the divine realm causing this to happen. We cannot stop people from their actions. We can suggest alternatives but cannot impose them. So, any action he took was his choice and anything that conspired to bring this sorry sequence of tragedies to an end was a confluence of events from many sources and factors and energies and not his direct choosing.