Washington (CNN) US investigators wiretapped former Trump campaign chairman Paul Manafort under secret court orders before and after the election, sources tell CNN, an extraordinary step involving a high-ranking campaign official now at the center of the Russia meddling probe. 
 
 The government snooping continued into early this year, including a period when Manafort was known to talk to President Donald Trump. 
 
 Some of the intelligence collected includes communications that sparked concerns among investigators that Manafort had encouraged the Russians to help with the campaign, according to three sources familiar with the investigation. Two of these sources, however, cautioned that the evidence is not conclusive. 
 
 Special counsel Robert Mueller's team, which is leading the investigation into Russia's involvement in the election, has been provided details of these communications. 
 
 A secret order authorized by the court that handles the Foreign Intelligence Surveillance Act (FISA) began after Manafort became the subject of an FBI investigation that began in 2014. It centered on work done by a group of Washington consulting firms for Ukraine's former ruling party, the sources told CNN. 
 
 The surveillance was discontinued at some point last year for lack of evidence, according to one of the sources. 
 
 The FBI then restarted the surveillance after obtaining a new FISA warrant that extended at least into early this year. 
 
 Sources say the second warrant was part of the FBI's efforts to investigate ties between Trump campaign associates and suspected Russian operatives. Such warrants require the approval of top Justice Department and FBI officials, and the FBI must provide the court with information showing suspicion that the subject of the warrant may be acting as an agent of a foreign power. 
 
 It is unclear when the new warrant started. The FBI interest deepened last fall because of intercepted communications between Manafort and suspected Russian operatives, and among the Russians themselves, that reignited their interest in Manafort, the sources told CNN. As part of the FISA warrant, CNN has learned that earlier this year, the FBI conducted a search of a storage facility belonging to Manafort. It's not known what they found. 
 
 The conversations between Manafort and Trump continued after the President took office, long after the FBI investigation into Manafort was publicly known, the sources told CNN. They went on until lawyers for the President and Manafort insisted that they stop, according to the sources. 
 
 It's unclear whether Trump himself was picked up on the surveillance. 
 
 The White House declined to comment for this story. A spokesperson for Manafort didn't comment for this story. 
 
 Manafort previously has denied that he ever "knowingly" communicated with Russian intelligence operatives during the election and also has denied participating in any Russian efforts to "undermine the interests of the United States." 
 
 The FBI wasn't listening in June 2016, the sources said, when Donald Trump Jr. led a meeting that included Manafort, then campaign chairman, and Jared Kushner, the President's son-in-law, with a Russian lawyer who had promised negative information on Hillary Clinton. 
 
 That gap could prove crucial as prosecutors and investigators under Mueller work to determine whether there's evidence of a crime in myriad connections that have come to light between suspected Russian government operatives and associates of Trump. 
 
 Origins of the FBI's interest in Manafort 
 
 The FBI interest in Manafort dates back at least to 2014, partly as an outgrowth of a US investigation of Viktor Yanukovych, the former Ukrainian president whose pro-Russian regime was ousted amid street protests. Yanukovych's Party of Regions was accused of corruption, and Ukrainian authorities claimed he squirreled millions of dollars out of the country. 
 
 Investigators have spent years probing any possible role played by Manafort's firm and other US consultants, including the Podesta Group and Mercury LLC, that worked with the former Ukraine regime. The basis for the case hinged on the failure by the US firms to register under the US Foreign Agents Registration Act, a law that the Justice Department only rarely uses to bring charges. 
 
 All three firms earlier this year filed retroactive registrations with the Justice Department. 
 
 It hasn't proved easy to make a case. 
 
 Last year, Justice Department prosecutors concluded that there wasn't enough evidence to bring charges against Manafort or anyone of the other US subjects in the probe, according to sources briefed on the investigation. 
 
 The FBI and Justice Department have to periodically seek renewed FISA authorization to continue their surveillance. 
 
 As Manafort took the reins as Trump campaign chairman in May, the FBI surveillance technicians were no longer listening. The fact he was part of the campaign didn't play a role in the discontinued monitoring, sources told CNN. It was the lack of evidence relating to the Ukraine investigation that prompted the FBI to pull back. 
 
 Renewed surveillance 
 
 Manafort was ousted from the campaign in August. By then the FBI had noticed what counterintelligence agents thought was a series of odd connections between Trump associates and Russia. The CIA also had developed information, including from human intelligence sources, that they believed showed Russian President Vladimir Putin had ordered his intelligence services to conduct a broad operation to meddle with the US election, according to current and former US officials. 
 
 The FBI surveillance teams, under a new FISA warrant, began monitoring Manafort again, sources tell CNN. 
 
 The court that oversees government snooping under FISA operates in secret, the surveillance so intrusive that the existence of the warrants only rarely become public. 
 
 For that reason, speculation has run rampant about whether Manafort or others associated with Trump were under surveillance. The President himself fueled the speculation when in March he used his Twitter account to accuse former President Barack Obama of having his "wires tapped" in Trump Tower. 
 
 The Justice Department and the FBI have denied that Trump's own "wires" were tapped. 
 
 While Manafort has a residence in Trump Tower, it's unclear whether FBI surveillance of him took place there. 
 
 Manafort has a home as well in Alexandria, Virginia. FBI agents raided the Alexandria residence in July. ||||| CLOSE Former Trump campaign chairman Paul Manafort and his longtime business associate Rick Gates are asking a federal judge to release them from home confinement while they await trial on financial charges brought by special counsel Robert Mueller. (Nov. 2) AP 
 
 Rick Gates, right, arrives for a bond hearing at the E. Barrett Prettyman Federal Courthouse in Washington on Nov. 6, 2017. Gates, a business associate of Paul Manafort, is facing charges for offenses allegedly discovered during the Russia investigation. (Photo: SHAWN THEW, EPA-EFE) 
 
 WASHINGTON – A federal judge on Monday ordered former Trump campaign chairman Paul Manafort and his associate Rick Gates to remain under house arrest with their movements tracked by GPS devices — until they offer up more bail money to assure their future appearances in court. 
 
 Federal prosecutors, who have leveled a 12-count indictment alleging a complex money laundering and tax fraud conspiracy, said they were "close" to reaching an agreement with the men's lawyers to free them from home confinement. 
 
 But U.S. District Judge Amy Jackson said the terms their release would not be eased until bail packages for both men were approved by the court. 
 
 "We are not talking about dangerousness," Jackson said in a brief hearing Monday morning. "We're talking about (the risk of) flight." 
 
 Jackson said she was "inclined" to eventually let both Manafort and Gates out of home confinement, and was even open to allowing them to travel within the United States so they could continue their consulting work, but not overseas. "No international travel is going to be a condition of this release," she said. 
 
 Manafort and Gates were charged this month with conspiracy, money laundering and acting as unregistered foreign agents in one of the first criminal cases to come from special counsel Robert Mueller's investigation of Russian tampering in the 2016 election and its possible connection to Trump's campaign. A grand jury alleged that they worked on behalf of pro-Russia factions in Ukraine, then laundered their profits into the United States to evade taxes. 
 
 Both men have been under house arrest since they surrendered to the FBI last week. 
 
 Their lawyers have struggled to come to an agreement with prosecutors over how much money they should have to put up before they are allowed to leave their homes. Prosecutors said the effort has been complicated because the men control a tangle of bank accounts, properties and other assets, many of which are connected to charges that they moved tens of millions of dollars through overseas banks during the past decade. 
 
 Prosecutors said they have determined Manafort's net worth to be about $28 million and wanted a package worth at least $10 million to assure his future court appearances. 
 
 Jackson said Manafort had pledged three personal properties totaling $7.5 million. While the judge said the properties were "a good start, it doesn't begin to cover" the $10 million in secured assets sought by the court. 
 
 Prosecutors said they were further from reaching a bail agreement for Gates, Manafort's business associate who also worked on Trump's campaign. He had promised to put up his house in Richmond, Va., as well as unspecified assets controlled by his parents. 
 
 More: Paul Manafort's lawyers will attack 'improperly obtained' evidence 
 
 More: Lawyers for Paul Manafort and Rick Gates mount first counterattack against Mueller charges 
 
 More: Mueller's bombshell: Special counsel charges Manafort, Gates and reveals aide's Russia contacts 
 
 In a court filing on Saturday, Manafort's lawyers said he would agree to put up $12.5 million of assets, including properties in New York and Florida and a large life insurance policy, to guarantee that he would show up at trial. They said he poses little risk of running from prosecution — in part because "there is much to question regarding the legal theories and the purported facts behind" money laundering and conspiracy charges Mueller's office outlined in the indictment last week. 
 
 Prosecutors called that offer insufficient on Sunday. They said in a court filing that Manafort had "not yet substantiated his net worth" and that the Trump Tower condo he offered to put up to secure his freedom might not be worth as much as he claimed. 
 
 "The government is not prepared to consent to a change in the current conditions of release at least until Manafort provides a full accounting of his net worth and the value of the assets that he proposes to pledge as part of his bail package," prosecutors wrote. 
 
 Last week, Manafort's lawyers Kevin Downing and Thomas Zehnle mounted their first counterattack against the federal charges, insisting in court filings that federal prosecutors had "embellished" the strength of their case. They wrote that they planned to seek “the suppression of evidence improperly obtained by search warrant, subpoena or otherwise." 
 
 FBI agents conducted an early-morning “no-knock” search of Manafort’s Virginia residence in July. Prosecutors said in an indictment unsealed last week that the search “revealed numerous documents, including documents related to lobbying." 
 
 U.S. District Judge Amy Jackson on Friday said last week she intended to schedule their trial for May 8. 
 
 Both Manafort and Gates face the prospect of long prison sentences. Prosecutors estimated in a filing that if Manafort is found guilty of all of the charges against him, federal sentencing guidelines would call for him to spend 12 to 15 years in prison. 
 
 More: The Paul Manafort indictment: His personal expenses, by the numbers 
 
 More: Who is Rick Gates, the man indicted with Paul Manafort? 
 
 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Indicted and influential: Who is Paul Manafort? | 1:16 Paul Manafort is a lobbyist, political consultant, lawyer and President Trump's former campaign chairman. Manafort has been indicted on money laundering as well as tax and foreign lobbying charges. USA TODAY 1 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Manafort, Gates ask for release from home arrest | 0:41 Former Trump campaign chairman Paul Manafort and his longtime business associate Rick Gates are asking a federal judge to release them from home confinement while they await trial on financial charges brought by special counsel Robert Mueller. (Nov. 2) AP 2 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Manafort's connection to 'the most dangerous mobster in the world' | 1:06 The charges brought against Paul Manafort reveal a link to one of the most dangerous mobsters in the world. Nathan Rousseau Smith (@FantasticMrNate) reports. Buzz60 3 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Paul Manafort has 3 passports; used a fake name on a phone and email | 1:07 Former Trump Campaign Chairman, Paul Manafort, who surrendered to the FBI on Monday, reportedly traveled to several counties using a phone and email account registered under a fake name. Buzz60 4 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Who is Rick Gates, the man indicted with Paul Manafort? | 1:05 Rick Gates, a longtime associate of former Trump adviser Paul Manafort, was charged in an indictment released Monday. USA TODAY 5 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Manafort leaves court after pleading not guilty | 0:33 Former Trump campaign chairman Paul Manafort left the federal courthouse in Washington Monday after pleading not guilty to charges related to conspiracy against the United States and other felonies. (Oct. 30) AP 6 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Manafort lawyer: No evidence of collusion | 1:19 Paul Manafort's attorney, Kevin Downing, said there's no evidence of collusion between the presidential campaign of Donald Trump and the Russian government. (Oct. 30) AP 7 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Paul Manafort turns himself in to the FBI | 0:43 Manafort, President Donald Trump's former campaign manager, has been a key figure in special counsel Robert Mueller's investigation. Video provided by Newsy Newslook 8 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS CNN: Former Trump adviser Paul Manafort was wiretapped by FBI | 1:05 Former Trump associate Paul Manafort was reportedly put under surveillance following a probe into his business dealings in 2014. Video provided by Newsy Newslook 9 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Robert Mueller subpoenas Paul Manafort's spokesman and former attorney | 1:05 Special Counsel Robert Mueller has issued two new subpoena in the investigation into President Trump’s campaign ties to Russia. Nathan Rousseau Smith (@FantasticMrNate) reports. Buzz60 10 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Manafort contacted Ukrainian operative using Trump campaign email | 0:54 President Trump’s former campaign manager, Paul Manafort, apparently contacted a Ukrainian political operative using his official Trump campaign email. Buzz60 11 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS FBI raids home of Trump's ex-campaign chairman amid Russia probe | 0:55 The FBI searched the home of President Trump’s former campaign chairman, Paul Manafort in July. Buzz60 12 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Paul Manafort swaps lawyers as Russia probe heats up | 2:10 It comes just a month after the FBI raided one of Manafort's homes. Video provided by Newsy Newslook 13 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Former Trump campaign manager to be questioned | 1:38 President Donald Trump's former campaign manager, a key figure in investigations about alleged campaign ties to Russia, has volunteered to be questioned by the House intelligence committee as part of its probe of the Kremlin's meddling in the 2016 election. (March 24) AP 14 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Paul Manafort registered as a foreign agent ... 5 years late | 0:50 Manafort and his consulting firm made over $17 million for work it did for a pro-Russian political party in the Ukraine. Video provided by Newsy Newslook 15 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Trump's former manager Paul Manafort reportedly pitched plan to benefit Vladimir Putin | 1:34 Questions about President Donald Trump's former campaign chairman, Paul Manafort, and his ties to Russia deepened following a report that he secretly worked for a Russian billionaire to advance the interests of Russian President Vladimir Putin in the mid-2000s. Read The Full Story Here: Trump's Former Manager Manafort Reportedly Pitched Plan to Benefit Putin Video provided by TheStreet Newslook 16 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS US probing offshore bank activity of Manafort | 1:46 U.S. Treasury Department agents have obtained information about offshore financial transactions involving President Donald Trump’s former campaign chairman, Paul Manafort, as part of an anti-corruption probe into his work, The AP has learned. (March 23) AP 17 of 18 Skip in Skip x Embed x Share CLOSE INDICTED AND INFLUENTIAL: PAUL MANAFORT IN THE NEWS Paul Manafort resigns in more Trump campaign shakeup | 0:49 Donald Trump thanked Paul Manafort for "his work guiding us through the delegate and convention process" after his campaign manager resigned. 18 of 18 Last VideoNext Video Indicted and influential: Who is Paul Manafort? 
 
 Manafort, Gates ask for release from home arrest 
 
 Manafort's connection to 'the most dangerous mobster in the world' 
 
 Paul Manafort has 3 passports; used a fake name on a phone and email 
 
 Who is Rick Gates, the man indicted with Paul Manafort? 
 
 Manafort leaves court after pleading not guilty 
 
 Manafort lawyer: No evidence of collusion 
 
 Paul Manafort turns himself in to the FBI 
 
 CNN: Former Trump adviser Paul Manafort was wiretapped by FBI 
 
 Robert Mueller subpoenas Paul Manafort's spokesman and former attorney 
 
 Manafort contacted Ukrainian operative using Trump campaign email 
 
 FBI raids home of Trump's ex-campaign chairman amid Russia probe 
 
 Paul Manafort swaps lawyers as Russia probe heats up 
 
 Former Trump campaign manager to be questioned 
 
 Paul Manafort registered as a foreign agent ... 5 years late 
 
 Trump's former manager Paul Manafort reportedly pitched plan to benefit Vladimir Putin 
 
 US probing offshore bank activity of Manafort 
 
 Paul Manafort resigns in more Trump campaign shakeup 
 
 Read or Share this story: https://usat.ly/2hKrw4o
– The FBI was listening in on Paul Manafort's conversations long before he became chief of the Trump campaign and it wiretapped him again as part of the investigation of alleged Russian election meddling, source say. The insiders tell CNN that Manafort was initially wiretapped under a secret court order in 2014 in connection with his work as a consultant in Ukraine. That investigation was dropped last year, apparently because there wasn't enough evidence to bring charges, the sources say, but the wiretapping resumed under another secret order which, like the first, was issued under the Foreign Intelligence Surveillance Act. It isn't clear when the second court order was issued, but the warrant extended until at least early this year, long after Manafort parted ways with the Trump campaign, the sources say. They say evidence collected suggests Manafort encouraged the Russians to help the Trump campaign—though the evidence is not conclusive. The New York Times, citing sources including lawyers and witnesses, reports that federal agents, apparently fearing Manafort would destroy evidence, picked a lock and entered without warning when they raided his Virginia home in July. The sources say that after the raid, special counsel Robert Mueller's prosecutor warned Manafort that they planned to indict him. (Mueller has made a move that could be very bad news for Manafort.)