Prosecutors like to muddy the waters by throwing around wild accusations about horrific crap, then only putting the guy away for something else.
Look at Ross Ulbricht. They tried him for running a website. They smeared his name by accusing him of hiring a hitman, but never gave him an opportunity to defend that accusation in court. Destroyed a lot of popular support. Tremendously effective, because people say, 'Well sure, that seems like a harsh sentence, but there were other things too. Didn't he hire a hitman, or rape his daughter or something?'
You don't need any evidence, because you're not charging him.
Because you're not charging him, he never gets the chance to shoot holes in your fabricated story.