Image caption John Sopko thinks he is now getting his message across

As a young lawyer in the 1980s, John Sopko made a name for himself fighting the mafia in Cleveland, Ohio.

Now he is taking a similarly fearless approach to uncovering fraud and mismanagement in the US aid effort in Afghanistan.

Since taking office as the United States Special Inspector General for Afghanistan Reconstruction (Sigar) last year, 61-year-old Mr Sopko has been making headlines with his unusually outspoken criticism of how US taxpayers' money is being spent.

In July alone, his office fired off eight separate reports highlighting concerns in a range of areas, from shoddy school construction and fraud by local contractors, to the failings of a new justice training programme.

"You've got to kick the tyres," he says in a typically forthright quote in his latest report. "You've got to verify that the money you gave to buy fuel bought the fuel."

Anti-corruption hotline

In his offices on the outskirts of Washington, Mr Sopko has a big map of Afghanistan to help him keep track of where his inspectors are working.

Poor contracting led to the deaths of a number of individuals John Sopko, Special Inspector General Afghanistan Reconstruction

His staff of 180 people includes 50 on the ground in Afghanistan. So far they have carried out checks in 23 of the country's 34 provinces.

His official website hosts a hotline for reporting fraud online. Afghans can also call a local number to register complaints in the main languages of Afghanistan.

And they do: the system has led to a number of investigations, arrests and prosecutions.

In September, a US state department employee pleaded guilty to receiving an illegal gratuity of $30,000 (£18,000) from a public official in Afghanistan. He was charged after Sigar received a tip-off on its hotline.

Mr Sopko is blunt about the scale of the waste his team has uncovered.

A recent case on his books involves a $34m military command centre, which he says the US army went ahead and built in Helmand even though they knew it would not be needed after the 2014 international troop withdrawal.

"Once you start a plan… it's very difficult to stop," he tells the BBC. "What we're going to do is to find out why they continued, even though the commanding general there specially told them a year before… don't build it, I won't use it, I won't need it."

Image caption Money that should have been spent stopping roadside bombs went astray

Another even more troubling case under investigation by Mr Sopko's team is the apparent theft of $1m from contracts to install protection systems against roadside bombs, the explosive devices favoured by the Taliban.

Afghan sub-contractors billed the US for blocking at least 250 drainage holes under highways where roadside bombs tend to be placed,

But the job was either improperly done or not completed at all.

"It's not just money being stolen from contract," Mr Sopko says. "Fraud kills. In this case, poor contracting led to the deaths of a number of individuals."

The US Defence Department told the BBC that it takes Mr Sopko's investigations very seriously, saying "the matter regarding the facility in Helmand Province remains under investigation".

The statement also pointed out that it was US military personnel themselves who first noticed problems with contractors installing roadside bomb defence systems and alerted the inspectors.

Few success stories

Mr Sopko's work has lead him to some sobering conclusions about the impact of reconstruction work in Afghanistan so far.

"We are so concerned about the lack of successes that I actually sent a letter to the secretary of state, to the secretary of defence and the head of [US international aid agency] USAid a number of months ago and said, give me your 10 most successful programmes. So we can learn from them," he told the BBC.

"They haven't been able to answer that question. So we're still looking for some successes."

It's clear that Mr Sopko's relentless barrage of criticism is not always what the US military top brass want to hear.

As he himself admits in his latest quarterly audit, 43 of the recommendations he made to the military for new measures to prevent insurgent groups getting access to US government grants were rejected outright.

"I am deeply troubled that the US military can pursue, attack and even kill terrorists and their supporters," he writes in the report, "but that some in the US government believe we cannot prevent these same people from receiving a government contract."

Image caption Road haulage is big business in Afghanistan

But the thick skin and determination that helped Mr Sopko pursue the feared crime boss James Licavoli back in Cleveland seem to be standing him in good stead.

By no means all of his recommendations go unheeded.

In August his office said they had managed to freeze the bank accounts of an Afghan trucking contractor accused of defrauding the US out of more than $77m.

Investigations into the case are continuing.

"I think we're getting the message across and some of the policy-makers are taking our advice very seriously," he says.

"We are slowly turning that ship of reconstruction around so that it will be done better, faster and more safely not only for our taxpayers but for our troops and civilians working in Afghanistan."

Sina Alinejad contributed to this report.