WASHINGTON — It was Michael Cohen's numerous contacts with a Russia-linked company and a sudden flow of foreign money into a bank account he controlled that led federal investigators to look into whether the money might be part of a plan to lift U.S. sanctions on Russia, according to court filings unsealed Wednesday.

Five search warrant applications, from the early stages of special counsel Robert Mueller's Russia investigation in 2017, were made public in response to requests from The Associated Press and other media organizations.

Cohen, once President Donald Trump's personal lawyer and confidant, was not charged by Mueller or prosecutors in New York with anything related to Russian collusion or illegal influence peddling. But the documents shed further light on how Cohen capitalized financially on his closeness to Trump immediately after the 2016 election.

Cohen quickly immersed himself in the Washington swamp his boss had pledged to drain. The lawyer cut deals to act as a highly paid consultant to several foreign and domestic companies with business interests linked to federal government decisions.

Cohen is now serving a three-year prison sentence for tax evasion, lying to Congress about a Trump real estate project in Moscow, and campaign finance violations related to hush-money payments he orchestrated to two women who claimed to have had affairs with Trump, the porn actress Stormy Daniels and erotic model Karen McDougal. Trump has denied the allegations.

Investigators said in the warrant applications that a corporate entity Cohen created, Essential Consultants LLC, received multiple deposits from foreign sources, including companies that investigators said had "significant ties to foreign governments or are entities controlled by foreign governments."

Essential Consultants received funds from U.S. and foreign corporations that appear to have approached Cohen "in connection with political objectives in the Trump administration," investigators wrote.

Among them were AT&T, which the documents show wanted Cohen's help securing approval for its merger with Time Warner, and pharmaceutical giant Novartis, which wanted "access and advice" after Trump pledged to fight high drug prices.

Investigators were especially curious about deposits of about $500,000 from an account linked to an investment management firm, Columbus Nova, LLC. The warrants tie that firm and the holding company that controls it to Viktor Vekselberg, a Russian oligarch with ties to Russian President Vladimir Putin.

In an application to search his Trump Organization email account, prosecutors said Cohen exchanged over 230 phone calls and 950 text messages with the CEO of Columbus Nova between Nov. 8, 2016, and July 14, 2017. There were no text messages or telephone calls before Election Day in 2016, prosecutors said.

Investigators at the time were examining whether any of the fund transfers were connected to Cohen's involvement in a plan, described months earlier in a New York Times story, to try to get the U.S. to lift sanctions on Russia.

"The United States continues to investigate if any of the payments or financial relationships described above, or other relationships described further below, were connected to Cohen's involvement in the distribution of a plan to lift Russian sanctions," a special agent wrote in a search warrant application in July of 2017.

A Columbus Nova spokesman wrote in an email to the AP that there was nothing nefarious about the frequent contacts between Cohen and company executives.

"They were working together so of course texted and called each other," the email said. "This was all known and investigated and wasn't even deemed worthy of being included in the special counsel's report."

Columbus Nova has described as false any allegation that Vekselberg used Columbus Nova as a conduit for payments to Cohen, saying it is solely owned and controlled by Americans.

Both Cohen and some of his clients apparently tried to keep his work secret. An AT&T consultant emailed a senior vice president at the company, saying that Cohen had "made the point several times that he doesn't list clients, doesn't talk about clients and hopes we won't be publicizing that he's working w/us. I assured him. And I hope he means it."

Novartis also didn't see the need to advertise that it was doing business with Cohen. In an April 2017 email exchange quoted in the search warrant documents, one executive wrote that they wanted to assess Cohen's ability "to secure high-level government meetings" and that there was "no need to divulge our relationship" with him.

Cohen has acknowledged offering his insights into Trump's administration to multiple corporate clients, but said he broke no laws in doing so. Cohen's attorney, Lanny Davis, said in a statement Wednesday night that "Cohen was not charged with anything to do with these allegations."

The newly unsealed material reveals nothing about Trump's own role in the crimes that put Cohen behind bars.

The warrant applications covered requests to search Cohen's email accounts, including one associated with the Trump Organization, They were blacked out in certain sections to protect the secrecy of an ongoing federal investigation into Cohen's campaign finance crimes.

Cohen has said he arranged payments to McDougal and Daniels at Trump's behest, which the president has denied along with the affairs.