A third person in the car in the Chappaquiddick scandal?

Adapted from Robert Whitcomb's "Digital Diary,'' in GoLocal24.com:

I'm looking forward to reading Donald Frederick Nelson's book CHAPPAQUIDDICK TRAGEDY: Kennedy’s Second Passenger Revealed (Pelican, 191 pages, sold in bookstores and online), in which he argues that there was a third person in the car that then Sen. Edward Kennedy drove off the Dike Bridge on July 18, 1969, killing  young Kennedy aide Mary Jo Kopechne and, as it turns out, probably dooming Kennedy’s presidential ambitions.

Mr. Nelson, a retired physicist who lives in Oak Bluffs, on Martha’s Vineyard, and Worcester, argues that Ms. Kopechne had climbed into the back seat of Kennedy’s car after some heavy drinking at a Kennedy party in a house on Chappaquiddick Island, the easternmost part of the Vineyard, and passed out, unbeknownst to Kennedy and another Kennedy “boiler room girl,’’ Rosemary (Cricket) Keough,  who was sitting in the front passenger seat.  When Kennedy drunkenly drove the car off the bridge and then, with Ms. Keough, escaped from the submerged car,  they had no idea  that there was somebody in the back seat, Mr. Nelson argues. In any case, Kennedy and his many enablers then went on to do a fairly effective coverup.

I still remember vividly the guys in the un-air-conditioned (but with salt tablets!), smoky newsroom of the old tabloid Boston Record American, where I spent the summer of 1969 as a news clerk, showing far more interest in the Chappaquiddick scandal than in the moon landing, the Vietnam War and Woodstock that summer.  It was like something out of the movie The Front Page. Vividly sordid.

Editor's note: Earlier versions of this comment said that Ms. Kopechne "drowned''. We changed that to "killed''. 

This was after Mr. Neal Costello, a reader, wrote to correct us with:  "She died a long and horrible death by asphyxiation, clinging to life for hours in an air pocket in the car. Perhaps she could have been saved if Kennedy had returned with help instead of only thinking of himself. ''