Shi Enhao, a leader in China’s growing underground church movement, disappeared last month — and it turns out he’s been in police custody, held on “suspicion of using superstition to undermine national law enforcement.”

Shi is one of as many as 150 million Chinese Christians who refuse to join the Communist Party’s Three-Self Patriotic Movement — the only Protestant church legal on the Chinese mainland. Children are not permitted at Three-Self churches, pastors are employed by the government and preach on assigned topics given them by Party officials.

Shi is the deputy chairman of the Chinese House Church Alliance. His daughter says the family learned weeks after his disappearance that he has been “criminally detained.” Criminal detention is the first step of the legal process that ends in a trial and the almost-inevitable conviction of a criminal offense, according to Radio Free Asia.

Shi has been among Christian leaders who have called on the Chinese government to halt its ongoing persecution of Beijing’s 1,000-member Shouwang Church.

Bob Fu, head of a New York-based advocacy group, ChinaAid, said he believes that the prolonged persecution against Shi “is premeditated and constitutes an attempt to frame Pastor Shi.”

“Against the backdrop of the persecution of one of Beijing’s largest house churches, the Shouwang Church,” said Fu, “this criminal detention of Pastor Shi is another sign of the increasing persecution of house churches across China.”

Fu called on police to release Pastor Shi and to “stop creating conflicts between church and state, which simply intensifies already tense church-state relations and the conflicts between the government and the populace.”

Shi first disappeared on June 12, immediately after he had been released from 12 days of administrative detention. Before he was even allowed to return home, police took him away to an unknown location.

He and and other lay leaders had been taken into police custody on May 31. Twenty-four hours later, the other detainees were released but Shi and a women’s group leader, Chang Meiling, were given 12-day administrative detention sentences.

A day later, police raided Shi’s home and took away books and other written materials.

Earlier he was arrested on March 4 by Domestic Security Protection officers and Religious Affairs Bureau officials. He had been preaching in the city of Nanyang. During that detention, his family reported, he was beaten – a common practice during interogation.