The Office of Inspector General offers the following guidance, which is also available at:
Report Fraud, Waste, and Abuse | Office of Inspector General (treasury.gov).
Emergency Rental Assistance (ERA) - In addition to filing a complaint with our office, we strongly recommend you also report ERA fraud to the local agency responsible for disbursing Rental Assistance funds (the entity who accepts and processes ERA applications for rental assistance) or the District of Columbia, Tribe, Tribally Designated Housing Entity (TDHE), Department of Hawaiian Home Lands (DHHL), State, Local government, or Territorial Agency that oversees the program. That agency may be able to take immediate action regarding the issue or redirect funds appropriately.
Please be aware that local law enforcement is a valuable resource for many issues of the type you may also refer to this Office. Local law enforcement may offer advantages such as the ability to interact quickly with the community, prosecute criminal offenses, and often has comprehensive victim, witness, and social services support programs which may better offer real-time assistance. Your State, Local, Tribal, Territorial or DC law enforcement agency with primary law enforcement jurisdiction is usually the same agency that responds to 911 calls.