The office, led by Letitia James, had been investigating the company for civil tax offenses since early 2019. The investigation has now escalated.

"We have informed the Trump Organization that our investigation into the Organization is no longer purely civil in nature," said Fabien Levy, a spokesman for the office. 

"We are now actively investigating the Trump Organization in a criminal capacity, along with the Manhattan DA."

A person familiar with the investigation told CNN that several investigators with the James's office, who are considered experts on the Trump Organization, have joined Vance's team.