The Public Security Intelligence Agency (PSIA) has identified the second son of Shoko Asahara — the founder of the now-defunct Aum Shinrikyo cult — as the de facto head of Aleph, the group regarded as Aum’s successor, it announced Tuesday.

The unnamed 31-year-old son of Chizuo Matsumoto, who was commonly known as Shoko Asahara, has been “involved in organizational decision-making and is leading Aleph’s operations,” the PSIA said in a statement. The agency has made moves to tighten restrictions on the group’s activities.

Matsumoto, who was executed in 2018, was the mastermind behind a series of deadly crimes carried out by Aum Shinrikyo, including the 1995 sarin gas attack on the Tokyo subway system that killed 14 people and injured thousands.