These are the likely fraudsters...

HART
Contracts
Auditors (lol!)
Contractors and Subcontractors (brother in law payments)
Politicians in charge
Lobbyists
The Mayor...audit him now and his family
The Council....ditto
Suppliers (overcharges and theft)
Payroll clerks padding hours worked
Pay to play
Materials suppliers

...and so on.  This is most of them.  Several of them in each category will red flag and they should be audited and then questioned.  Many of them will rag out the guys at the top to get off the hook.  Chart out eveything, and report it to the public asap.