Demi Moore is ending her marriage to fellow actor Ashton Kutcher, she said Thursday.

Moore, 49, and Kutcher, 33, were wed in September 2005. The couple's relationship became tabloid fodder in recent months as rumors swirled about Kutcher's alleged infidelity.

"It is with great sadness and a heavy heart that I have decided to end my six-year marriage to Ashton. As a woman, a mother and a wife there are certain values and vows that I hold sacred, and it is in this spirit that I have chosen to move forward with my life. This is a trying time for me and my family, and so I would ask for the same compassion and privacy that you would give to anyone going through a similar situation," she said in a statement.

"I will forever cherish the time I spent with Demi," Kutcher said in a tweet Thursday. "Marriage is one of the most difficult things in the world and unfortunately sometimes they fail."

Moore said in 2007 that her May-December relationship with the star of "That '70s Show" and "Punk'd" -- who is 15 years younger than Moore -- "caught us both by surprise." Kutcher, now starring in "Two and a Half Men," became a stepfather to Moore's three daughters -- Rumer, Scout and Tallulah Belle -- from her 13-year marriage to actor Bruce Willis. Moore and Willis divorced in 2000 but remain friendly.

Natalie Wood death probe reopenedThe Los Angeles County Sheriff's Department announced Thursday that it was reopening its investigation of the 1981 death of actress Natalie Wood. Officials ruled at the time that her drowning while boating off Santa Catalina Island was an accident. She was on a yacht with husband Robert Wagner and guest Christopher Walken. The two men had an argument, Wood left and couldn't be found on the boat later, Wagner has said. "Recently sheriff's homicide investigators were contacted by persons who stated they had additional information about the Natalie Wood Wagner drowning. Due to the additional information, Sheriff's homicide bureau has decided to take another look at the case," the department said in a written statement.

BOOK AWARDS: Jesmyn Ward won the National Book Award for fiction for "Salvage the Bones," and, in the nonfiction category, Stephen Greenblatt won for "The Swerve." The awards were presented Wednesday night in New York. The award for poetry went to Nikky Finney for her fourth collection, "Head Off & Split." The prize for young people's literature went to Thanhha Lai for "Inside Out and Back Again."