Special counsel Robert Mueller has amassed hundreds of thousands of records as part of his investigation into former Trump campaign chairman Paul Manafort, according to a court filing on Friday that shed new light on the scope of the ongoing federal probe.

Lawyers from Mueller's team said they have issued 15 search warrants related to the federal investigation so far, and obtained more than "400,000 items," including bank records, tax returns and emails. Many of the documents, which were described by prosecutors in a status report on Friday, fell into the hands of federal investigators after the FBI raided Manafort's Virginia apartment earlier this year.

The items also include photographs of three dozen electronic devices that Manafort used to conduct business with foreign governments and clients of his lobbying firm, according to the status report, which prosecutors filed Friday at the U.S District Court for the District of Columbia.

"Given the volume of discovery in this case, the government also produced to defendants certain documents that it identified as 'hot,'" prosecutors wrote, noting that of the 400,000 items more than 2,000 were deemed particularly important.

The filing reveals that federal prosecutors are looking closely at bank records from Cyprus, Saint Vincent and the Grenadines — locations where Manafort and his business partner, Rick Gates, are alleged to have laundered money and kept offshore bank accounts.

Both men were indicted in late October on 12 counts, ranging from conspiracy against the United States to money laundering. Manafort struck an $11 million bail agreement with prosecutors late last month that could soon get him released from house arrest.

Lawyers involved with the special counsel investigation said several unrelated documents, like "deposition testimony given by the [Manafort or Gates] in another matter," were also obtained during their search at Manafort's home. Some of those items are "privileged," meaning they may be protected by an attorney-client relationship.

The filing comes days after Justice Department officials said the special counsel investigation has cost American taxpayers at least $3.2 million so far. Several White House aides and former Trump campaign hands have also been forced to shell out significant funds to cover legal costs related to the probe.

In addition to Manafort and Gates, former Trump adviser George Papadopoulos and ex-national security adviser Michael Flynn have both pled guilty to separate charges in the federal investigation.