The investigation of Michael Cohen, President Donald Trump's former lawyer, began at least nine months before federal agents raided his home and office, according to search warrants made public Tuesday.

The newly released documents show that the first FBI warrant was executed on July 19, 2017, targeting Cohen's Gmail account and seeking messages from all of 2016 up to July 2017. Special counsel Robert Mueller's team turned over documents to federal prosecutors in New York on Feb. 8, 2018.

Some 20 days later, the U.S. Attorney's Office in the Southern District of New York received search warrants for the same account granting them the right to access Cohen's emails from Nov. 13, 2017, to the end of February 2018.

The search warrants reveal that Mueller's investigation of Cohen began nearly a year earlier than previously known.

The FBI raided Cohen's office and hotel suite on April 9, 2018, seeking evidence of bank fraud and hush money payments to two women, porn star Stormy Daniels and Playboy model Karen McDougal, who claimed they had affairs with Trump. In addition to the emails, the investigators seized cell phones and at least 12 audio recordings, federal prosecutors said in court documents released last year.

The newly released search warrants show that the probe into Cohen largely focused at the outset on his taxi businesses and false statements to banks as part of an effort to "relieve him" of some $22 million in debt he owed on taxi medallion loans. In communications with banks, Cohen reported that his net worth cratered between 2014 and 2017 — dropping from $75.9 million to negative $12.2 million due to the depreciation of his real estate assets and taxi medallion investments.

View all the Cohen documents

"From my review of a summary of bank records that were scheduled by forensic accountants, I have learned that Cohen had approximately $5 million in cash and cash equivalents as of Sept. 30, 2017," an FBI agent says in the court documents.

It's unclear how an investigation that started with suspected bank fraud led to a probe of possible campaign finance crimes related to the payouts to Daniels and McDougal. The roughly 19 pages of the search warrant that detail the hush money scheme are all redacted, suggesting that it remains part of an ongoing probe.

The documents show that Mueller's office was also investigating Cohen for a previously-unknown allegation: that he was acting as an unregistered foreign agent.

Thousands of dollars from companies with overseas ties began flowing into Cohen's bank accounts in the days and months after Trump took office, according to the search warrants.

From January 2017 to August 2017, Cohen received seven monthly payments totaling $583,332 from Columbus Nova, an investment management firm controlled by Renova Group. The court documents describe Renova Group as a Switzerland-based company controlled by Russian billionaire Viktor Vekselberg.

Spokespersons for Columbus Nova say the management firm is owned and controlled by Americans and not Vekselberg, whose links to Cohen emerged last year when Stormy Daniels' attorney Michael Avenatti detailed the transaction in a dossier posted to Twitter.

Cohen was also paid $600,000 by South Korean aircraft company Korea Aerospace Industries, and a Kazahkstani bank, Kazkommertsbank, deposited $150,000 into one of his accounts, according to the search warrants.

An FBI agent wrote in the documents that the payments appeared to stem from "political consulting work, including consulting for international clients on issues pending before the Trump administration."

Cohen, who is slated to begin a three-year prison sentence in May, was ultimately not charged with acting as an unregistered foreign agent.

The warrants describe the use of a "triggerfish" cellphone surveillance device to pinpoint the location of Cohen who was using a room at the Loews Regency hotel in Manhattan. They also sought and obtained a "pen register" or "trap and trace" warrant to find out who Cohen was calling and receiving phone calls from, but without the ability to listen or monitor those calls.

Last December, Cohen was sentenced to three years behind bars for what a Manhattan federal court judge called a "veritable smorgasbord" of criminal conduct.

Cohen had earlier pleaded guilty to making secret payments to Daniels and McDougal, lying to Congress about the president's business dealings with Russia, and failing to report millions of dollars in income.

The president and White House have denied the affairs.

Cohen's attorney Lanny Davis, speaking ahead of the search warrants' release, said Monday that it "only furthers his interest in continuing to cooperate and providing information and the truth about Donald Trump and the Trump organization to law enforcement and Congress."