Antasari Azhar was detained because

Indonesian police have detained the country’s top anti-corruption official as a suspect in the murder of a prominent business executive.
     [21C] Antasari Azhar was questioned on Monday as a witness, but police told reporters that based on strong evidence he would now be interrogated as a suspect.
    Nasrudin Zulkarnaen, a former director of a state-owned business, was killed in a drive-by shooting in March.
     [22C] Analysts say that the scandal is a huge blow to the Corruption Eradication Agency.
    The independent agency, known as the KPK, was set up in 2003 to lead a huge push by President Susilo Bambang Yudhoyono in tackling corruption.