Olympics Day 10: Michael Phelps says he means it

LONDON (CNN) -- Michael Phelps, the most decorated Olympian in history, said Monday that he really means it when he says he is retiring.

"I'm done. I don't know if people really believe me, but I am actually finished. I'm retiring," he told CNN's Becky Anderson.

"D-O-N-E. Done," she pressed.

"Yes -- I'm done," he insisted.

Phelps, the U.S. swimmer, not only shattered the record for the most medals ever won by a single person at the Olympics -- with 22, including 18 golds -- but also made history as the first swimmer to win gold in two different events in three consecutive Olympics.

On Monday, he also defended the gold medal-winning swimmer Ye Shiwen, who has been suspected -- without proof -- of doping after her remarkable victories.

"It's kind of sad that people have a great swim and that's the first thing they say," Phelps said of the Chinese 16-year-old.

"People who work hard -- it shows. There are people who just jump to that conclusion sometimes, and it's not right."

American gold medal gymnast Gabby Douglas was back in action Monday on the uneven bars, but turned in a disappointing performance and came eighth.

Hometown favorite Beth Tweddle took bronze in the event, behind Russia's Aliya Mustafina, who claimed gold, and Kexin He of China, who earned silver.

Another gold medalist found himself at the center of another controversy Monday as Kenyan police confirmed that steeplechase winner Ezekiel Kemboi was under investigation on suspicion of trying to stab a woman on a date before he left for the Games.

The woman accused Kemboi of making sexual advances, said deputy police spokesman Charles Owino, without naming the alleged victim. Kemboi is a policeman himself, according to Owino.

Kemboi said that he was the victim of attempted extortion and that police had not given him a fair hearing, Owino said.

And the International Olympic Committee announced that it disqualified American judoka Nicholas Delpopolo from the men's 73-kg judo event for a doping violation. It stripped the 23-year-old of his seventh-place finish after he tested positive for a cannabis byproduct.