How long does it take to audit a church?

So there's a priest who's had "allegations" of a financial nature against him. The bishop's office reported that they will have an audit done to confirm or deny these allegations. The church is about as big as they get (for a Catholic church anyway). They have about 10 mes every Sunday in two separate buildings. They also built a school. I'm not sure if the school's finances are being audited. How long should it take an auditing firm to find out whether or not there's merit to the allegations?