However, that claim may be fraudulent, which could cast doubt on the letter's credibility.

He had to cast doubt on my credibility so no matter what I found, I couldn't have him thrown in prison.

But he's already cast doubt on Billy's credibility with those repeated "he says."

With the doubts that had been cast on her credibility, however, she'd have difficulty proving it.

Indeed, according to the Times, the air actually "cast doubt on Mr. Chambers's credibility."

Her campaign blunders cast doubt on her credibility as a candidate and her ability as a potential governor.

Mr. Meese's admission cast new doubt on Colonel North's credibility, a central issue in the 11 weeks of hearings.

I would very much like to hear what the Commission has to say about this, as it does cast doubt on its credibility.

But two dozen other scientists gave interviews belittling Zach's views and casting doubt on his credibility.

He was also said to have provided statements intended to cast doubt on the women's credibility.