Sen. Dianne Feinstein at a news conference in Washington in 2014. Associated Press/J. Scott Applewhite Sen. Dianne Feinstein of California on Thursday cast suspicion on the memo written by Deputy Attorney General Rod Rosenstein that recommended the firing of James Comey as FBI director, saying in a statement she had grown more "troubled" by its contents after reading it three times.

"The memo appears to have been hastily assembled to justify a preordained outcome," Feinstein said, adding that it read more like a "political document" than "meaningful analysis."

"Given Rosenstein's legal expertise and 27-year Justice Department career, I would have expected him to produce a detailed and comprehensive rationale for Director Comey's firing, including input from the agents and staff who worked with Director Comey," she continued.

Feinstein, who is the top Democrat on the Senate Judiciary Committee, also said the memo cited months-old quotes from op-ed articles and media appearances and no current insights from within the FBI.

Feinstein's statement also called for Rosenstein and Attorney General Jeff Sessions to recuse themselves from the "appointment, selection, and reporting of" a special counsel to investigate contacts between associates of President Donald Trump and Russia.

Thursday's statement is one several Feinstein has issued since Comey's Tuesday firing, with each appearing more critical than the previous.

Her original statement on Comey's firing was two sentences long and said his replacement "must be strong and independent and will receive a fair hearing in the Judiciary Committee." The following day, Feinstein questioned the timing of Comey's firing and whether it was due to the ongoing Russia investigation.

"If Director Comey was fired to stifle the FBI's Russia investigation — and the timing of this action makes that a real possibility — that simply cannot be allowed to happen," she said.