How does the ACSU function?
The anti-corruption and security unit (ACSU) in the IPL explained

There are at least two ACSU officers providing cover at the team hotel as well as the grounds on both match as well as non-match days • AFP
The ACSU is the ICC watchdog, hired by the BCCI to provide cover to the players and monitor the activities both on the ground and the team hotel.
The ACSU duty usually begins between one and two months before the tournament. In addition to carrying out reconnaissance at every venue, one of the initial exercises the ACSU officers carry out, as part of the awareness programme, is to impart education to players on the history of corruption in cricket. They are then told how the modus operandi of the bookies, how they usually groom players, how the bookies operate, how the players can be lured, the different ways a bookie can make the initial approach, what needs to be done in case of an approach, if there is a threat to the player's life or if someone is trying to blackmail him what steps need to be taken, the dos and don'ts in every situation. That template is listed out to the players and officials from every team before every IPL.
Although the exact number of the ACSU workforce is not known, at every IPL venue there are at least two ACSU officers providing cover at the team hotel as well as the grounds on both match as well as non-match days. In addition, every year a certain number of active Indian police officials are recruited on a temporary basis to lend a helping hand. From the 2013 season, in the wake of the spot-fixing scandal, the BCCI decided to appoint an extra vigilance officer who will travel with every team.
In 2012, the BCCI appointed its own domestic anti-corruption unit under the stewardship of former ICC ACSU head Ravi Sawani. Along with him there are four other officers - all former cops - who have been exclusively hired to put an anti-corruption structure in place and install programmes designed to educate all the teams in domestic cricket in India.
No. ACSU works independently. The BCCI's anti-corruption unit is not involved in the IPL.
The ACSU officer does not have the power to arrest anyone. Based on the evidence he can prepare a report by referring to the tournament code of conduct before passing the information to the BCCI's ACU, which then will forward the report to the board's disciplinary committee, which has the powers to determine the punishment.
In 2008, the ACSU served the IPL merely in the role of observers. In 2009 the BCCI initially hired a private security agency when the tournament was shifted to South Africa but were eventually persuaded to bring the ACSU on board. That contract, which stipulates that the BCCI pays a one-time fee to the ACSU for the year, has been renewed every year till date.
Considering the ACSU acts like an undercover agent, they remain invisible and so do their activities. Reportedly, the ACSU frequently receives information from players, coaches, team or franchise officials about approaches and suspicious behaviour, but they are never made public. The ACSU acts with discretion and in case the matter is serious, the BCCI is made aware.
The hotline number for the ACSU is displayed prominently in press boxes and dressing rooms.
Nagraj Gollapudi is an assistant editor at ESPNcricinfo