Head straight North from the starting point when heading into the party. This will get Edward right into the party. he will talk with the Guard for a minute to be admitted inside. Head on in toward the marker to start the next part of the memory.
Go over to the left immediately after the zoom in on Rogers. This will put Edward behind some cover and block the line of sight Rogers had on him. Follow it over to the bench that sits nearby. Sit down there and wait for Rogers to come to you. When he does, kill him.