China's ruling Communist Party has announced it is launching an investigation into former domestic security chief Zhou Yongkang, who was once one of the country's most feared leaders.
A party watchdog, the Central Commission for Discipline Inspection, said on its website that it is investigating Mr Zhou for serious violations of party discipline.
Until his retirement in 2012, Mr Zhou was one of nine leaders in the party's ruling inner circle, whose members had until now been considered off-limits for prosecution in an unwritten rule aimed at preserving party unity.
The announcement ended months of speculation over Mr Zhou's fate that had built up as several high-ranking officials and businessmen and dozens of other known associates came under investigation.
One after another, they disappeared into the custody of party investigators, hinting at the problems that lay ahead for Mr Zhou.