It’s taking longer than expected to review whether operational issues at Ontario’s air ambulance service affected patients, according to a panel looking into the case.

In a statement issued Tuesday, the provincial coroner’s office said the process is taking longer than previously thought due to the “large number of files” that are under review.

The investigation into Ornge, beset by operational and managerial difficulties this year, explores whether there are any patient deaths that could have been prevented.

A previous review of 10 deaths found that none had been “materially affected” by difficulties at the air ambulance service, under investigation for financial irregularities.

The current review explores all deaths involving Ornge between January 2006 and June 2012.

In an August 2012 interview with CTV Toronto, deputy chief coroner Dan Cass said the review doesn’t seek to lay blame, but rather is searching for lessons in the deaths.

That same month, a legislative committee investigating Ornge’s business dealing wrapped up for the summer, after testimony from several witnesses including former CEO Chris Mazza.

In regards to the patient report, Ontario’s Chief Coroner Andrew McCallum expected the investigation to be complete this fall.

When the now-delayed report is eventually complete, the coroner plans to make it available to the public.