Alan Dershowitz commented Monday on Deputy Attorney General Rod Rosenstein after President Trump told Chris Wallace he is answering written questions from Special Counsel Bob Mueller.

Dershowitz said Rosenstein presents a "striking example of bias" in one way by "still being in charge of the investigation."

After former Attorney General Jeff Sessions recused himself from the Russia probe, Rosenstein became the de facto leader who controls Mueller. However, with the acting-appointment of Matt Whitaker, that role moves to his purview.

Dershowitz said that any allegation by Mueller of obstruction of justice can be met with the defense that Rosenstein likely sanctioned whatever action is in question.

"How can you both be in charge of the investigation and the main witness for the defense?" Dershowitz asked.

He said that Mueller and his team will go through Trump's written answers "with a fine toothed comb" -- looking for a "perjury trap."

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Dershowitz warned that Trump or any defendant can be subjected to perjury allegations even if they tell the truth in some cases.

He added that after the Mueller probe concludes, the government should look to alter the composition of the FISA court that approved the warrant to surveil former Trump associate Carter Page.

Dershowitz suggested a "permanent group of defense attorneys with security clearances" at-the-ready to challenge any warrant brought to the court by the feds in the future.

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