The U.S. Department of the Treasury is opening an investigation into the delay of the production of $20 bills with Harriet Tubman.

Acting Treasury Inspector General Rich Delmar stated his intentions in a letter to Senate Minority Leader Chuck Schumer, according to NPR.

"As part of this work, we will interview the stakeholders involved in the new note design process," Delmar wrote in the letter. The message was written on June 21.

The Treasury announced Tubman would be printed on the bill in 2016, during the Obama administration. She was supposed to replace Andrew Jackson by 2020, in time for the 100th anniversary of the passage of the 19th Amendment, which granted women the right the vote. As Blavity previously reported, the process was interrupted in May when Treasury Secretary Steven Mnuchin announced the bill wouldn’t go into circulation until 2028.

“The primary reason we have looked at redesigning the currency is for counterfeiting issues,” Mnuchin said. “Based upon this, the $20 bill will now not come out until 2028. The $10 bill and the $50 bill will come out with new features beforehand.”

Two days before Delmar’s letter, Schumer sent one of his own, requesting an assessment of "the involvement of other participants in the interagency process related to the redesign – including the Secret Service, Federal Reserve, and the White House – to ensure that political considerations have not been allowed to infect the process for designing American currency."

Delmar’s investigation will take approximately 10 months. He promised to act if he found evidence of misconduct.

"If, in the course of our audit work, we discover indications of the employee misconduct or other matters that warrant a referral to our Office of Investigations, we will do so expeditiously," Delmar wrote.

The Washington Post reports Mnuchin stands by his reasoning for the delay.

“The timeline for issuing new notes is not a political process, and the timeline for issuing a new $20 note remains consistent with the prior Administration’s,” a Treasury spokesman said in a statement. “As the Department and Bureau of Engraving and Printing have consistently stated, the only consideration with regard to the redesign schedule of our Nation’s currency has been security and potential counterfeiting threats.”

If Tubman’s face ends up on the bill, she will be the first Black person featured on U.S. currency.