Attorney General Bill Barr has some explaining to do.

That’s according to Sen. Ron Wyden (D-OR), who on Monday pressed the attorney general to share what he knows about President Donald Trump’s alleged attempts to intervene in a federal case against a Turkish bank accused of sanctions violations.

The reported contents of a manuscript by former National Security Adviser John Bolton have added more weight to the senator’s questions.

The bank, Halkbank, was ultimately charged in October with six counts related to a scheme to evade U.S. sanctions on Iran, but the prosecution was politically fraught: Trump’s lawyer Rudy Giuliani represented a Turkish gold trader involved in the scheme, Reza Zarrab, and at one point claimed to have met with Turkish President Recep Tayyip Erdogan in 2017 to discuss a “state-to-state resolution in this case.”

And as Wyden noted in his letter Monday, the charges against Halkbank came just days after Turkey invaded northern Syria, opening the doors to political backlash in America.

“I am concerned that absent these actions by the Turkish government, the Administration’s interference in favor of Turkey’s Halkbank requests could have undermined years of effort by U.S. law enforcement, and may still do so,” Wyden wrote.

In October, Bloomberg News reported that Trump “assigned” Barr and Treasury Secretary Steven Mnuchin to “deal with” Erdogan’s pleas that the United States not charge Halkbank. The outlet also reported that Trump urged then-Secretary of State Rex Tillerson to persuade the DOJ to drop the case against Zarrab, something Tillerson reportedly refused.

And more recently, The New York Times reported that Bolton’s book manuscript described a conversation Bolton and Barr had in which they shared concerns that Trump was doing favors for — or at least, that he could appear to exert an undue influence on behalf of — for Erdogan, as well as for Chinese President Xi Jinping. (The DOJ has said the Times’ report “mischaracterizes” the conversation.)

“Did President Trump, or did anyone at his direction, ever instruct you to take any action with regard to Halkbank, or any co-conspirators such as Reza Zarrab?” Wyden asked Barr in a letter Monday, one of several questions the senator posed.

Later, he asked of Barr or other senior DOJ officials “ever appeal[ed] directly to the Treasury Department, at any level, on behalf of President Trump or the Turkish government?”

The senator also noted that, despite the DOJ’s quibbling of Bolton’s reported manuscript, a Treasury Department official had confirmed some aspects of the story.

“As was publicly reported, when Prime Minister Erdogan raised concerns directly with President Trump in April 2019, the President referred the issue to the Executive Branch departments responsible by law for the investigation and enforcement of economic sanctions — the Treasury and DOJ,” a Treasury Department official told Wyden last year, which the senator cited in his letter Monday.