Well it's been speculated that when Mangum was dropped off she first got into Roberts car to do some planning. Bissey may have come out in time to see them get out "together".
Rita Cosby quoted him as saying "I noticed a car drive up and two young women get out," so he is wrong on that account. He also says "And at that point, the young women were coming back out of the house, getting into the car and driving away." No way that's true either because Mangum was helped/carried to the car with the help of a player. Anything the guy says is suspect.