Washington (CNN) Federal prosecutors investigating associates of Rudy Giuliani have launched a broad investigation that could include criminal charges ranging from conspiracy, obstruction of justice, campaign finance violations and money laundering, according to a subpoena sent to at least one witness and seen by CNN.

The broad range of charges encompassed in the subpoena include conspiracy to defraud the US, acting as an unregistered foreign agent, obstruction of justice, making false statements to federal officials, wire fraud, money laundering and violations of federal election laws that prohibit the use of straw donors and foreign money in US elections.

Giuliani has not been accused of any wrongdoing. He has previously told CNN he has not heard from prosecutors.

"I have not seen any subpoena that looks for communications or documents from Mayor Giuliani or Giuliani Partners," said Robert Costello, a lawyer for Giuliani. "It would not be surprising given that two of the indicted individuals had a business and a legal relationship to Mayor Giuliani and Giuliani Partners. Of course that relationship had nothing to do with the indictment. All the SDNY had to do was ask us and we would have given them whatever they wanted because Mayor Giuliani has nothing to hide and did everything in a proper and legal way."

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