The last professional photos of Marilyn Monroe, unstyled and informal, go up for auction

This photo was taken during the filming of the movie "Niagara," in upstate New York in 1952.

Allan "Whitey" Snyder

A few weeks before Marilyn Monroe died, she took part in what would turn out to be her last professional photo shoot.

Paired with photographer George Barris, whom she had come to trust, the images captured the star in honest and unguarded moments. Those photos and other Monroe memorabilia are now up for auction in New York.

Shortly after she was fired from the never-completed film "Something's Got to Give!" the actress turned to Barris to help her tell her side of the story.

"Barris had known Marilyn for a number of years and had first met her when she was filming 'The Seven Year Itch,'" said Dean Harmeyer, senior specialist for auction house Paddle8.

"In the summer of 1962, Marilyn's career was at a bit of a tenuous spot and she developed a bit of a reputation in Hollywood for being difficult on the set," Harmeyer said. 

More than 150 photos from Monroe's final shoot are part of a wider online auction being held this week by Paddle8.com

While they were commissioned for Cosmopolitan magazine, dozens of the pictures have never been seen before.

The photos were taken during two sessions. One was inside a Hollywood home, in which Monroe was prepped by a professional hair and makeup team. The other was an informal shoot on a Santa Monica beach.

"Her makeup has not been done, she has not had her hair styled. She said that these were the favorite photographs she had ever had taken of her by George Barris and they're marvelous in their candor. They capture her essence and her spirit," Harmeyer said. 

The ocean side shoot would be the very last time Monroe was professionally photographed.

Barris, who died in 2016, once told CBS News about the very last snapshot he took of Marilyn Monroe.

"She said, 'Are we finished?' and I said, 'No, let's just take this last one.' So, she puckered up her lips and she sort of blew a kiss to me and she said, 'This is for you and the world,' and we walked off that beach and I never saw her again," Barris said. 

The online auction at Paddle8.com is live right now, and wraps up on Friday.