The Montana attorney general’s office is investigating whether the Central Asia Institute broke any laws that govern non-profits in Montana.
Assistant Attorney General Jim Molloy said investigators have reviewed thousands of pages of documents and interviewed Mortenson and others connected to the charity.
He declined to say what the investigation has revealed but said his office would be updating the public within a month.
The state’s probe does not involve the merits of the accounts contained in Mortenson’s books, he said.
Mortenson has denied wrongdoing and has kept out of the public eye since having heart surgery last year. In December, the Central Asia Institute said in its year-end letter that Mortenson would no longer be involved in the charity’s day-to-day management and that it was looking at expanding its three-person board of directors.