Mark Whitaker is finally having to face the music, along with Bill Cosby. The former Newsweek editor, whose biography of the actor/comedian, Cosby: His Life and Times, was published on September 16, has come under fire for opting to largely exclude the claims, by various women, that Cosby sexually assaulted them. On Monday night Whitaker addressed the situation via his Twitter account, admitting he was "wrong" not to dig deeper into the issue. Nonetheless, Whitaker said, he is standing by the book...for the time being.

The renewed attention to Cosby's alleged misdeeds was sparked by a stand-up routine from comedian Hannibal Buress, that went viral in October. The clip, in which Buress calls Cosby "a rapist," led to an outpouring of comments on Twitter. This then sparked a renewed press interest in various claims, over the years, from women who said Cosby had sexually assaulted them.

Whitaker, and his book, which offers a largely positive picture of Cosby, began coming under more direct fire last week. In a piece on the Daily Beast, called "The Agony of Cosby's Biographer," Whitaker's response to the situation seemed mixed. While he admitted to the Beast's Lloyd Grove that future editions of his book might need to be changed, he also defended his subject. Whitaker told Grove: “He’s paid a big price… The show [a planned NBC sitcom] has been yanked. The reruns of The Cosby Show have been taken off the air. He’s routinely called a rapist everywhere. That’s a big price.”

After David Carr, writing in the New York Times, took Whitaker (along with himself, and other members of the media) to task for side-stepping the repeated claims about Cosby, the biographer felt compelled to respond.

Carr's Monday story led to two tweets, Monday evening, from Whitaker. In a message directed at Carr (@carr2n), Whitaker wrote: "I was wrong to not deal with the sexual assault charges against Cosby and pursue them more aggressively." He then added: "I am following new developments and will address them at the appropriate time. If true the stories are shocking and horrible."

According to figures from Nielsen BookScan, which tracks roughly 80% of print sales, Cosby: His Life and Times has sold just under 5,900 copies, to date. A spokesperson for Simon & Schuster said: "Like everyone else, Mark is following the story and the new allegations as they emerge. He will speak to it at the appropriate time, but nothing has been decided yet about future editions."