Volodymyr Ariev, a member of Parliament who is an ally of President Petro O. Poroshenko, readily acknowledged that the intention in Kiev was to put investigations into Mr. Manafort’s activities “in the long-term box.”
“In every possible way, we will avoid irritating the top American officials,” Mr. Ariev said in an interview. “We shouldn’t spoil relations with the administration.”
The Ukrainian investigators had been tracing money paid to Mr. Manafort and a New York law firm, Skadden, Arps, Slate, Meagher & Flom, by figures in the political party of Viktor F. Yanukovych, the Russian-leaning Ukrainian president who was ousted by street protesters and fled the country in 2014. Mr. Manafort was a longtime adviser to Mr. Yanukovych, working with him to revamp his public image and acquire a pro-Western patina that helped him win the presidency in 2010.
The new government established a special prosecutor to pursue corruption in the former administration. By late last year, the prosecutor, Serhiy Horbatyuk, had opened about 3,000 cases, including four related to Mr. Manafort’s consulting for the former president and his political party.
The order issued in April isolated these four investigations. The cases were not closed, the prosecutor general’s office said in a statement, but the order blocked Mr. Horbatyuk from issuing subpoenas for evidence or interviewing witnesses.
“We have no authority to continue our investigation,” Mr. Horbatyuk said in an interview.
One inquiry dealt with possible money laundering in a single $750,000 payment to Mr. Manafort from a Ukrainian shell company. The payment formed one part of the multimillion dollar transfers to Mr. Manafort from politicians in Ukraine that underpin indictments filed by Mr. Mueller in federal court in Washington and Virginia. Before the case was frozen, prosecutors had subpoenaed records from Ukrainian banks.
Another concerned a former chairman of the Ukrainian Parliament’s foreign relations committee, Vitaly Kalyuzhny, who had signed nine of 22 entries designated for Mr. Manafort in a secret ledger of political payoffs uncovered after the 2014 revolution. The ledger showed payouts totaling $12.5 million for Mr. Manafort.
The handwritten accounting document, called in Ukraine the Black Ledger, is an evidential linchpin for investigating corruption in the former government. Mr. Manafort denied receiving under-the-table payments from the party and his spokesman said the ledger might be a forgery.
The other two cases looked at Skadden Arps, which wrote a report with Mr. Manafort’s participation that was widely seen as whitewashing the politically motivated arrest and imprisonment of Mr. Yanukovych’s principal rival, Yulia V. Tymoshenko.
Newsletter Sign Up
Thank you for subscribing.
An error has occurred. Please try again later.
You are already subscribed to this email.
Two months before Ukraine’s government froze the cases, Mr. Horbatyuk reached out to Mr. Mueller’s office with a formal offer to cooperate by sharing evidence and leads. Mr. Horbatyuk said that he sent a letter in January and did not receive a reply, but that the offer was now moot, since he has lost the authority to investigate.
But entries in the ledger appear to bolster Mr. Mueller’s money laundering and tax evasion case against Mr. Manafort, said Serhiy Leshchenko, a lawmaker who has closely followed the investigation. They indicate, for example, payments from Ukraine to a Cypriot company, Global Highway Limited, that was also named in an indictment Mr. Mueller filed in federal court in Virginia this year. The company covered hundreds of thousands of dollars of Mr. Manafort’s bills at a high-end men’s clothing store and antique shop in New York.
In another move seeming to hinder Mr. Mueller’s investigation, Ukrainian law enforcement allowed a potential witness to possible collusion between the Trump campaign and Russia to leave for Russia, putting him out of reach for questioning.
The special counsel’s office has identified the man, Konstantin V. Kilimnik, Mr. Manafort’s former office manager in Kiev, as tied to a Russian intelligence agency. Mr. Kilimnik was also under investigation in Ukraine over espionage, but no charges were filed before he left the country, sometime after June. During the 2016 campaign, Mr. Kilimnik met twice with Mr. Manafort. In December, a court filing in the United States said Mr. Kilimnik was “currently based in Russia.”
But in the United States, Mr. Mueller’s office appears still keenly interested in Mr. Manafort’s ties to Russia. Among the questions Mr. Mueller would like to ask Mr. Trump, according to a list provided to the president’s lawyers, was: “What knowledge did you have of any outreach by your campaign, including by Paul Manafort, to Russia about potential assistance to the campaign?”
In Kiev, the missile sale was seen as a political victory for Mr. Poroshenko, indicating American backing for his government in the war in eastern Ukraine against Russia-backed separatists and against the threat of a wider Russian intervention in the country. After Ukraine announced on April 30 that it had received the missiles, Mr. Poroshenko posted on Facebook that “the long-awaited weapon arrived in the Ukrainian Army.”
Apart from the missiles, the Ukrainian government is propped up with about $600 million in bilateral aid from the United States annually. Mr. Poroshenko’s office did not respond to a request for comment on Tuesday.
David Sakvarelidze, a former deputy prosecutor general who is now in the political opposition, said he did not believe that the general prosecutor had coordinated with anybody in the United States on the decision to suspend the investigations in Ukraine, or that there had been a quid pro quo for the missile sale.
Ukrainian politicians, he said, concluded on their own that any help prosecuting Mr. Manafort could bring down Mr. Trump’s wrath.
“Can you imagine,” Mr. Sakvarelidze said, “that Trump writes on Twitter, ‘The United States isn’t going to support any corrupt post-Soviet leaders, including in Ukraine.’ That would be the end of him.”
Last summer, another member of Parliament, Andrey L. Derkach, initiated an investigation into leaks to the news media about Mr. Manafort’s dealings from Ukrainian law enforcement, saying they put at risk vital American aid to Ukraine. He has openly opposed any Ukrainian role in aiding the special counsel’s investigation.
Ukraine, Mr. Derkach said in an interview, would be taking grave risks if it assisted in what he called a politicized investigation in the United States. In Ukraine, he said, “everybody is afraid of this case.”