The state attorney general's office has subpoenaed Grand Prix of Boston, its CEO John Casey as well as the national Indycar organization as it begins an investigation into the group's the now-canceled Boston event, WCVB reported.

The attorney general's office is reportedly investigating the financing of the event, originally scheduled for Labor Day weekend but canceled last April.

The amount of money held by the company at the time of its cancelation was not enough to reimburse ticketholders, a lawyer for the event told the network, describing the outstanding debts as “not a small amount.”

WCVB estimated the cost could be around $2 million, noting that the organization claimed to have sold over 22,000 tickets at an earlier point this year.

The network also obtained a list of sponsors, some of whom contributed hundreds of thousands of dollars to event organizers. 

You can read the full report on WCVB’s website.