Letters Show Jackie Kennedy's Other Side

Recently discovered letters attributed to the late Jacqueline Kennedy Onassis contain some surprising tough-love marital advice to her then sister-in-law, Joan Kennedy.

CBS News correspondent Michelle Miller reports that the handwritten memos and letters show a side of Jackie O. the public hasn't seen before. The former first lady is trying to help her sister-in-law Joan through her doomed marriage to Senator Ted Kennedy

"The content is beyond description," said auctioneer Bill Panagopulos. "In these letters she comes across as a spitfire... in these letters, spitfire may be an understatement."

Panagopulos is putting the notes and a handful of other items found in an abandoned storage unit in Hyannis Port on the auction block.

The auctioneer is confident that the letters are authentic. "I've sold a lot of Jackie's letters and there's simply no doubt about it," he said.

Panagopulos believes they were written around 1979 because the writer references the Senator's failed 1980 Presidential bid.

The letters' writer pulls no punches.

One reads, "You're no prude or fool – if he goes off to a Refugee Conference in Geneva – you don't like to think about it – but you wouldn't be surprised if he had a big blow-out in Paris with Hooter or someone."

"It's probably coming from the heart," Panagopulos said.

Four heart-felt pages that continue with: "But having your own little black phone billed to John Warnecke so that you can talk to Mootsie or Pootsie every night – right in the house with his wife & children – and bringing them there when you're away. What kind of woman, but a sap or a slave, can stand that & still be a loving wife – & care about him & work like a dog for him campaigning."

Panagopulos, who has sold more than 40,000 items in the last 12 years, is staking his reputation on the find.

When asked how much he thinks the letter will fetch, his only answer was, "good question."

If past auctions of Jackie's letters are any indication, these could sell for anywhere from $5,000 to $20,000.