A federal grand jury investigating activities surrounding Rudy Giuliani’s back-channel campaign in Ukraine has demanded legal documents that include records of extravagant spending at Trump hotels and millions of dollars in financial transfers by Lev Parnas and Igor Fruman, two key operatives who carried out the plan, according to a source familiar with the demand.

The documents requested by a subpoena that was issued in Florida last week could shed light on whether other people, including foreign nationals, were trying to influence the top levels of government and impact the 2020 presidential campaign.