Police in Hangzhou, eastern China’s Zhejiang province, arrested 21 people in relation to an illegal fundraising investigation into JC Group, a private fund company that defaulted on billions of yuan of debt.

Jay Wei, founder and chairman of JC Group, is among five suspects detained for alleged fundraising fraud, a criminal charge that could lead to the death penalty, according to the Hangzhou police Wednesday.

Sixteen other people, including JC Group executive Gu Deyao, were arrested on suspicion of illegally taking public deposits, a crime subject to as much as 10 years in jail.

A probe was launched in April into suspected illegal fundraising by Hangzhou-based JC Group after police received reports from the eastern province’s securities watchdog and whistleblowers.

JC Group and its affiliates control at least six private fund management firms and one fund sales company. The companies raised as much as 30 billion yuan ($4.5 billion) from investors by last May, according to a report on the initial findings of a securities watchdog investigation seen by Caixin. The report showed that by October they had missed repayment on more than 17 billion yuan.

Related: Head of Multi-Billion Dollar Fund Empire Faces ‘Illegal Fundraising’ Investigation