You don't know what you're talking about.  I can tell by your spelling you've relied on gossip not research.  Yes, I think Ted was treated easily by the law.  Remember Ted's 2  brothers were killed by the CIA, an "independent agency of the United States."  I also believe they should have performed an autopsy on Mary Jo Kopechne. 

The following theory sounds reasonable, something you probably never heard before.  Mary Jo Kopechne got drunk and went out to lay down in Kennedy's car.  She passed out in the back seat.  Soon after, Ted and another woman from the party got into the car.  They soon noticed a cop car behind them.  Ted was drunk.  He darted off the road onto a dirt one and accidentally drove off the dangerous Chappaquiddick bridge.  He and the young woman got out with their lives.

The next morning Ted appeared in the dining room of the inn where he was staying.  An elderly couple saw him and exchanged conversation with him.  He walked away from them but they were still watching him when 2 men came in and told Ted something that made him turn white with shock. 

Someone had seen the car under the water and called the cops.  They found Mary Jo Kopechne dead in the car.  They also retrieved a pocketbook.  It belonged to the other woman Ted was with.

He did not kill Mary Jo.  It was an accident.  Does that sound reasonable?