The Kennedys are the foremost liberal family in the US political establishment but they have been haunted by tragedy.

John F Kennedy was America's 35th president when he was assassinated in Dallas, Texas, in 1963. Lee Harvey Oswald was arrested but he too was murdered before facing trial.

JFK Junior, centre stage at his father's funeral, died in a 1999 plane crash

John's brother, Robert Kennedy, was shot dead in June 1968 while campaigning in Los Angeles for the Democratic presidential nomination.

Long before that, another brother of President Kennedy had died in a plane crash in 1944 and his sister was killed in another plane crash in 1948. A second sister was forced into a mental home by their overbearing father, Joseph.

The late president's remaining brother, Senator Edward Kennedy, ruined his chances of also running for the presidency after he was involved in a car accident in which he apparently left his passenger to die.

A car he was driving plunged off a bridge and into water on Chappaquiddick Island near the exclusive resort, Martha's Vineyard.

A passenger in the car, 28-year-old Mary Jo Kopechne, was found dead in the car's back seat about 10 hours later.

Mythical status

Of the late Robert Kennedy's sons, Michael was killed in a skiing accident and David died of a drugs overdose.

And in 1999, JFK Junior - along with his wife and sister-in-law - died when the light aircraft he was piloting plunged into the Atlantic.

The so-called "curse of the Kennedys" has a long reach. A nephew of Edward Kennedy was accused of rape, then acquitted. Other Kennedys have had drug problems.

The private life of the late president has been the subject of much scrutiny amid allegations about his compulsive womanising and ruthless political methods.

One biography by the American writer, Seymour Hersch, accused the late president of being a drug addict.

But despite the scandals, the Kennedy name has kept its mythical status in the United States.