Only $30,000 of the $103,000 taken in by the 26.4.26 Foundation was used for the organization's purpose, co-founder Ryan Graney of Nashville, Tenn., told The Associated Press last week.
Graney said she filed complaints with office of Tennessee Attorney General Robert Cooper Jr. and the FBI after her former partner, endurance athlete Robbie Bruce, could not account for the missing money.
Investigators in Tennessee are looking into the organization, Cooper's office confirmed in an email Tuesday, and Connecticut Attorney General George Jepsen said he offered help and also was told Cooper's office was making the investigation a priority.
"He fully understands the gravity of the situation," Jepsen said in an interview Tuesday.
An FBI spokesman said the agency does not comment on specific investigations but confirmed that there are ongoing fraud investigations related to Newtown.
The IRS was also asked to investigate in a letter from U.S. Sen. Chris Murphy, a Connecticut Democrat. An IRS spokesman did not immediately respond to a phone call and email seeking comment.
Bruce didn't return repeated telephone messages. No one answered the door at his apartment last week.
The idea behind the 26.4.26 Foundation was for runners to participate in marathons, raising money for each of the 26 miles they ran and dedicating each mile to one of the 26 victims of the 2012 school shooting in Newtown - 20 children and six educators. The fundraising effort was featured in Runner's World magazine and was the subject of several local news stories.
The charity held its first marathon in Nashville a week after the shooting, with more than 1,000 participants raising $30,000. Another was held in New Hampshire last April. More than 1,400 runners raised about $22,000 for the foundation, organizers said. The charity also received donations from runners in other events, Graney said.
The $30,000 was presented last January by Bruce to a youth sports center in Newtown.
Graney said she noticed something was amiss last spring, when she discovered suspicious charges to the foundation's PayPal account, including $1,200 billed for paddleboards.
"I went on (Bruce's) Instagram page," she said, "and he had posted a picture of a paddleboard in the back of his truck."
Graney said she confronted Bruce and he promised to meet her and go over the organization's finances. She said he never showed up and then cut off contact with her in September.
She said she shut down the foundation's website and contacted authorities.
"If I knew what was going on, I would have stopped it sooner," she said. "I feel terrible. I couldn't sit by and let this happen."