As Xi Jinping’s anti-graft crackdown enters its second year, media attention has recently turned to one of the campaign’s powerful – but silent – allies: the audit office. While it is common knowledge that audits have given important leads for anti-corruption officials, the National Audit Office (NAO) has mostly worked behind the scenes, as it keeps its inner workings confidential. It's a world that conjures up images of thick stacks of ledgers and tedious number-crunching, but auditors opened up to the Communist Party’s youth league newspaper, Beijing Youth Daily , about the extent of the office’s role in the crackdown and how the results could cause shockwaves. Xi has vowed to severely punish both the lowest-ranking and most powerful cadres, dubbed “flies” and “tigers”. The NAO’s main role is to provide clues to the Central Discipline Inspection Commission (at the forefront of graft investigations); the Ministry of Supervision; the top prosecutor, or Supreme People’s Procuratorate; and the Ministry of Public Security. Liu Jiayi, the NAO’s director, said at last year's National Auditing Conference that audits, "under the current situation", should tightly follow the general request of “anti-corruption, reform, and development”. The case against China’s former railways minister, Liu Zhijun, was triggered by clues from the audit office, the report said, without providing further details. A bribery case implicating a Ministry of Finance official this year was uncovered by a standard audit. Liu was given a suspended death sentence with a two-year reprieve last July. Last year, audit offices across the country scrutinised more than 150,000 companies and government departments, “saving” more than 450 billion (HK$566 billion) in funds and directing more than 2,400 cases to relevant authorities for further investigation. Some 400 cases were sent to the Ministry of Justice and anti-graft agencies last year – 20 of which were related to the graft probe against state-owned oil giant PetroChina. During the process of investigation, even within the audit office, it is highly confidential Auditor In the recent audit report on an electricity transmission project, more than 6.68 billion yuan was found to have been misused or spent without proper oversight. In April, the NAO started a massive audit of the State Grid’s chairman, Liu Zhenya, around the time when the anti-graft crackdown set its sights on the power industry. It was deemed the largest such audit ever carried out on a state-owned enterprise. So far this year, the audit office said there have been 54 cases – 13 of which were sent to the discipline watchdog, 12 to the security ministry, 12 to the prosecutor’s office and 17 to other government bodies. However, it stopped short of publicising details about the cases to protect the integrity of investigations. ”It is professional ethics to obey confidentiality,” an anonymous source at the NAO told the the newspaper. “During the process of investigation, even within the audit office, it is highly confidential.” Even within the National Audit Office, auditors are kept in the dark about what their peers are working on and they are banned from asking colleagues for information. ”To enhance the confidentiality, most people only know things they are in charge of. Only a few know the general situation,” the source said. The auditors told the Youth Daily that leads to many major cases were in fact discovered during standard financial audits – and often an anomaly appears in the smallest of details. ”Clues leading to many major cases originated from some tiny violations [such as in a] money transfer or a contract,” the report cited sources as saying. Auditing in China is a regular, systematic process meant to ensure accurate, clean accounts in state bodies and corporations. The auditing officials told the newspaper that government officials, powerful individuals, public funds and state-owned assets or resources have come under particular scrutiny since Xi came to power in 2012. Nowadays, auditors must not only examine disparate accounts and sets of numbers, but discover the connections between one set of data and others. This way, auditors can follow the money trail. “The case is often that an audit is on company A, but because of money transition, it extends to company B, then to company C and D. And in the end the severe violation is seen at company S,” the report said.