The South Korean government has seized the personal information of thousands of U.S. citizens as part of its investigation into a controversial Christian group in the country, alarming religious freedom advocates.

The Shincheonji Church of Jesus, a religious group that counts more than 300,000 followers worldwide, has come under intense scrutiny after South Korean authorities traced the country's first large-scale coronavirus outbreak to its services in February. Authorities, who are pursuing murder charges against the group's leader, collected the personal information of U.S.-based Shincheonji practitioners, including passport numbers and addresses, after seizing a list of all its followers. The data seizure has alarmed American practitioners of the faith, particularly after public leaks of that data led to death threats against believers.

"There is a genuine sense of fear that there will be a lot of repercussions, you know, socially, and also professionally," Michelle Lee, an American Shincheonji practitioner, told the Washington Free Beacon. "In South Korea, the list of congregation and congregant's information has been leaked and people have been receiving death threats, messages, calls, verbal assaults in person."

The South Korean government did not return requests for comment.

The Shincheonji controversy has alarmed U.S. officials and religious freedom experts, some of whom have expressed concerns that Seoul is using the pandemic as an opportunity to crack down on a religious group that is widely disparaged as a cult. The issue also serves as a case study of what happens when well-intentioned pandemic policy ends up infringing on religious freedom.