I don't think it's a simple answer. If you placed a hold at the time of deposit without any type of proof that it was fraudulent, then you can hold the amount over $5525.00 for 7 days. The $5525.00 falls under next day availability since it's a cashier's check. If you have suspicion that it was fraudulent at deposit, then as Randy said, just don't accept it.
Once it was deposited, if you receive information that it is fraudulent at a later date, then you can hold the full amount due to reasonable cause to doubt collectability for 7 business days (from date of deposit). Make sure you notate all information you have received that has caused you to doubt the collectability (notice it's being returned, called bank and received information that it's fraudulent) etc. As I believe examiners would look for the reasons you used this exception hold on a next day item.