NEW YORK – The brother of an associate of President Donald Trump's lawyer Rudy Giuliani is under examination as part of a closely watched campaign finance conspiracy case, a federal prosecutor said Friday.

Assistant U.S. Attorney Nicolas Roos told a judge that Steven Fruman, the younger sibling of Giuliani business client Igor Fruman, could have been involved in the alleged scheme to buy influence by funneling hundreds of thousands of dollars to U.S. politicians and campaign committees.

Roos said the younger sibling lied about his bank accounts and his businesses when questioned by government paralegals who were examining his suitability to serve as a co-signer on Igor Fruman's $1 million bond package.

Saying that Steven Fruman "could be involved" in some of the actions alleged in the criminal case, Roos said, "it seems he was trying to conceal something." The prosecutor did not elaborate.

Defense lawyer Todd Blanche said the younger Fruman ultimately provided the requested financial information. He also questioned whether prosecutors have incriminating evidence against Steven Fruman.

Saying that someone who may be involved in the case "may not be suitable as a co-signer," U.S. District Court Judge Paul Oetken said he would not immediately intervene with the examination of the younger Fruman's finances.

The case has drawn the attention of House investigators pursuing impeachment proceedings against Trump because Parnas and Fruman helped Giuliani seek damaging information in Ukraine against the family of former vice president Joe Biden, who is seeking the 2020 Democratic presidential nomination to run against Trump.

Saying he did nothing wrong, Trump has repeatedly branded the proceedings a witch hunt. Trump has also reaffirmed his support for Giuliani.

Also on Friday, the judge rejected a defense request to free Igor Fruman from the home confinement and GPS monitoring restrictions that are part of the bond package.

He issued the ruling after Blanche argued that the Belarus-born suspect is a Miami, Florida resident who has been a U.S. citizen for 15 years, has young children he must take to school and has no intention of fleeing.

However, Roos said Fruman, 53, had businesses in Ukraine and elsewhere outside the country, along with a history of taking "circuitous international travel routes" and access to a private jet.

Roos also noted that Fruman and co-defendant Lev Parnas were arrested on Oct. 9 at Dulles International Airport in Virginia as they prepared to leave the U.S. with one-way tickets to Vienna, Austria.

Blanche contended that Fruman had bought a one-way ticket because round-trip booking would have been far more expensive and he didn't have a precise return date.

There was no certainty that Fruman planned to return to the U.S., said Roos, who noted that the prosecution case is strong with evidence of international wire transfers of funds, text messages, and emails.

"There's a compelling need to keep tracking him and make sure he's in the same location," Roos said.

Agreeing, Oetken ruled that continued GPS monitoring and home detention were "reasonably necessary to assure the appearance of the defendant" at future court hearings in the case.

Fruman and Parnas, who was born in Ukraine, are accused of scheming to buy influence by funneling hundreds of thousands of dollars in foreign funds to U.S. government officials and political action committees. The indictment alleges they conspired with an unidentified Ukraine government official and a Russian businessman who agreed to supply funds for the scheme.

U.S. election laws prohibit foreign nationals from making campaign contributions and bar donors from making campaign contributions in the name of someone else.

The questioned funding in the conspiracy case includes a $325,000 contribution to a political action committee formed to support Trump. The funds never passed through the financial accounts of the listed contributor, and instead came from another company, prosecutors allege.

Two other co-defendants, David Correia, a native U.S. citizen, and Andrey Kukushkin, who was born Ukraine, are charged with funneling campaign contributions to secure government approvals for a planned cannabis business.

All four suspects have pleaded not guilty.

Giuliani has acknowledged that he received $500,000 from Fraud Guarantee, a Parnas and Fruman company. Online business records show the company had no few customers and negligible income.

USA TODAY reported in October that U.S. counterintelligence agents were investigating Giuliani's business dealings with Parnas and Fruman as early as February or March of 2019. Separately, federal investigators in New York have been investigating Giuliani's finances and work in Ukraine, The Wall Street Journal reported.

This article originally appeared on USA TODAY: Impeachment: Feds probe brother of Igor Fruman, a Giuliani associate