"This investigation includes, but is not limited to, potential violations of Georgia law prohibiting the solicitation of election fraud, the making of false statements to state and local governmental bodies, conspiracy, racketeering, violation of oath of office and any involvement in violence or threats related to the election's administration," Willis writes in the letter.
News of Willis' investigation comes just two days after it was revealed that the Georgia secretary of state's office had launched its own investigation into Trump's phone calls to state officials, and in the midst of the U.S. Senate's ongoing impeachment trial as Democrats seek to convict Trump on charges that his efforts to thwart his election loss helped to incite the Jan. 6 insurrection at the U.S. Capitol.
"The timing here is not accidental given today's impeachment trial," said Trump senior adviser Jason Miller in response to the probe. "This is simply the Democrats' latest attempt to score political points by continuing their witch hunt against President Trump, and everybody sees through it."
A spokesperson for Willis' office did not immediately respond to ABC News' request for comment. A spokesperson for Raffensperger's office also declined to comment on the development.
Willis' letter specifically notes that her office currently has "no reason to believe that any Georgia official is a target of this investigation."
Trump's first known call to Georgia state election officials took place in December as the state was conducting a signature match audit in Cobb County, outside Atlanta. According to a recording of the call, Trump insisted to a chief investigator in Raffensperger's office that “something bad happened” in the state, telling the official, “When the right answer comes out, you'll be praised."
Later, when ABC News obtained audio of his hour-long Jan. 2 call to Raffensperger in which Trump pleaded with him to find the exact amount of votes needed to overturn his election loss, election law experts argued Trump could have violated as many as three separate state laws.
Trump has previously denied any wrongdoing, and his impeachment lawyers filed a brief last week disputing that Trump "acted improperly in that telephone call in any way."
Editor's note: A previous version of this story stated that during a December call, former President Donald Trump told a Georgia elections investigator to "find the fraud" while a signature match audit was underway in one county, according to an individual familiar with the matter. ABC News has since obtained a recording of the call, and Trump did not say those exact words. This story has been updated to remove those quotes.