This question deals with how a hypothetical crime would be tried.
Hypothetical situation: The police find two people who have been locked in a room for the past 6 hours. In the room with them is a dead body. Murder! For the sake of simplicity, they somehow know that no one came in or out of the room during those six hours, an eye witness perhaps, but they do know that 3 people went into the room, and only 2 were able to walk out. Survivor A says survivor B was the murderer, and vice versa. All the evidence the police have neither fully incriminates one nor exonerates the other. As they have figured it, there's a 60% chance person A did it and a 40% chance person B did it.
How would this case be tried? There's not enough evidence to make a solid case against one, and all the police have is a hunch. And since America's court system processes one case at a time, these two suspects would be tried separately and would likely both be acquitted as there's simply not enough evidence to convict one. So how would this be tried?