There was a man who was living with the Skakels,surving as their tutor, who had a history of mental problems, in later years he admitted doing it and ended up killing himself. I believe the wrong man is in jail.
To whom did this guy admit having killed the girl? Did this come out in Skakil's trial? Given what you've said,why are they pursuing the Kobe Bryant thing? Claiming that this dead guy did it is,IMO,a far more plausible scenario than the Kobe Bryant defense.
The man you write of is named Ken Littleton, and he is very much alive. His life was ruined for years by endless hassling from the police over this matter, and they could never prove a thing because he did not do it. If they had found anything against him, he would have been arrested and tried long ago. They never found anything. He had just come to the Skakels and just settled in the day of the murder. If he did the murder, he sure found the custom-made set of clubs once owned by the Skakels' mom pretty fast in order to murder Martha with one of the clubs just a few hours after he arrived.