Former Trump campaign manager Paul Manafort arrives for a hearing at the E. Barrett Prettyman U.S. Courthouse on May 23, 2018 in Washington, DC.

With Paul Manafort's jury deliberating bank and tax fraud charges, President Donald Trump refused to say Friday whether he would pardon his ex-campaign chief.

"I don't talk about that," Trump told reporters on the White House's South Lawn when asked about a pardon for Manafort.

But Trump also said: "I think it's very sad what they've done to Paul Manafort."

"I think the whole Manafort trial is very sad," Trump said. "He happens to be a very good person."

A few miles away in Alexandria, Virginia, 12 federal jurors began their second day of weighing charges against Manafort brought by special counsel Robert Mueller.

Mueller is continuing to investigate whether Trump obstructed justice in a Justice Department probe of Russian interference in the 2016 presidential election and whether Trump campaign officials colluded with the Kremlin-backed meddling.

Mueller has reportedly eyed Trump's firing of FBI Director James Comey in spring 2017 after the president allegedly told Comey: "I hope you can see your way clear to letting this go, to letting Flynn go."

Michael Flynn, who was briefly Trump's national security adviser, has pleaded guilty to making false statements and is cooperating with Mueller's probe.

That investigation has infuriated Trump, who on Friday again called it "a rigged witch hunt."

"Mr. Mueller has a lot of conflicts," Trump said. "Mr. Mueller is highly conflicted. In fact, Comey is like his best friend. I can go into conflict after conflict."

While Comey and Mueller worked together, there are no indications they were close personal friends.

"Let him write his report," the president said. "We did nothing. There was no collusion."

"If he was doing an honest report, he'd do it on the other side," Trump said, referring to the 2016 presidential campaign of Democratic nominee Hillary Clinton.

"When you look at criminality and you look at the problems, take a look at what they did, including colluding, the other side," the president added.

Trump on Friday also said, once again, that Manafort "worked for me for a very short period of time" on his campaign.

In fact, Manafort joined that campaign in mid-March 2016, with responsibility for wrangling committments to Trump from delegates to the Republican National Convention.

Manafort then was promoted to campaign manager in June, and remained in that role until mid-August, when he resigned after reports that he may have been secretly paid nearly $13 million from a pro-Russia political party in Ukraine from 2007 through 2012.

Manafort is accused in the Virginia case of failing to pay taxes on millions of dollars earned from that party, failing to disclose to the IRS the existence of offshore accounts he controlled, and defrauding banks by giving false statements about his financial status in an effort to obtain loans once the income stream from the Ukrainian party ceased.

The 69-year-old GOP political operative has pleaded not guilty in that case, as well as in a related case in U.S. District Court in Washington, where he is accused of money laundering and failing to register as an agent of a foreign government.

In the Washington case, he is also charged with trying to tamper with witnesses who could be called to testify against him.

That alleged effort led a federal judge in June to revoke Manafort's $10 million bond and to jail him.

Manafort's former business associate Rick Gates, who also held a senior position in Trump's campaign, pleaded guilty to conspiracy and making false statements, and testified against Manafort at his trial.

Gates is cooperating with Mueller's probe in an effort to win leniency at sentencing.