Special counsel Robert S. Mueller III’s investigation cost the government about $16.7 million in the first 10 1/2 months, new documents show. (Andrew Harnik/AP)

Special counsel Robert S. Mueller III’s investigation cost the government about $16.7 million in its first 10 1/2  months, new documents show, a not insignificant price tag that is sure to be used by President Trump and his allies to attack the probe.

From the beginning of October through the end of March, Mueller’s tab increased by about $10 million, counting what he spent on personnel and other costs and what his investigation caused other Justice Department components to spend, the documents show. Mueller had previously reported a cost of about $6.7 million for his first 4-1/2 months in office.

Mueller has made significant progress since he was appointed a little more than a year ago to investigate whether the Trump campaign coordinated with Russia to interfere with the 2016 election. He has charged 19 people and three companies. Five people have pleaded guilty to various charges, including former Trump national security adviser Michael Flynn, former deputy campaign chairman Rick Gates and former campaign foreign policy adviser George Papadopoulos.

Trump and his supporters, though, have relentlessly criticized Mueller’s work, and recent polling suggests that although a majority of Americans still support the investigation, that support is slipping.

Even before the newest documents were released, Trump had taken aim at the cost of the investigation, writing on Twitter earlier this month, “At what point does this soon to be $20,000,000 Witch Hunt, composed of 13 Angry and Heavily Conflicted Democrats and two people who have worked for Obama for 8 years, STOP!”

The cost is not necessarily out of line with prior special investigations, and the documents note that Mueller is reporting what his work has caused other Justice Department components to spend — which previous special counsels have not. Mueller reported about $4.5 million in expenditures from October through March, and indicated his investigation caused other Justice Department components to spend about $5.5 million.

The money that Mueller spent directly came from an indefinite appropriation for independent counsels, which the Justice Department determined could be used to fund Mueller’s work. The department said the other money would have been spent by Justice Department components for the investigations “irrespective of the existence” of the special counsel’s office.

From October through March, Mueller, who has a team of 17 lawyers, spent $2.7 million on personnel costs, the new documents show. He also spent more than a half-million dollars on travel and more than $880,000 on rent, communications and utilities, the documents show.

By comparison, Lawrence E. Walsh, the prosecutor who investigated Reagan administration officials in the Iran-contra affair, spent $47.4 million during his eight-year investigation. Former independent counsel Kenneth W. Starr spent more than $52 million investigating President Bill Clinton, and the five independent counsels appointed to look into various Clinton-related matters during the 1990s spent more than $100 million.