Originally posted by The Dr. who fixed Lucy:
He didn't want Fredo to disappear into the night, possibly to go to Roth and divulge even more Corleone family secrets, possibly even to set up a hit on Michael again. He wanted Fredo in his sights, so that he could kill him when Mama died.
I agree about mike wanting to keep Freddie close. But at that time in havana, when he tells Freddie to come with him in the car he didn't tell him that because he was worried about Freddie going back to Roth. He even says to Freddie that Roth is dead. at the time he didn't know that Roth was still alive.
DS
