A female follower of the outlawed Falun Gong spiritual sect suffered a lengthy beating by police before being thrown to her death from a high window, according to the Falun Dafa Information Centre.
Yu Xiuling died on September 19, after a fall from the fourth-story of a police station in the north-eastern province of Liaoning.
A police official is denying any knowledge of the event.
According to the centre, 32-year-old Yu was arrested on September 14 for being a Falun Gong practitioner.
On September 19, she was taken to the police station and beaten for a number of hours after she refused to renounce her beliefs in the Buddhist-based sect.
The centre says after the beating, two police officers threw Yu, who was still alive, from the fourth-storey window.
The centre says her husband was told she had jumped to her death.
The US-based centre says more than 280 followers have died in custody since the group was outlawed as an "evil cult" just over two years ago.
Reports of such deaths have proved difficult to verify but independent human rights groups have put the toll at more than 150.
Analysts assert China's communist leadership considers Falun Gong a threat to social stability and a challenge to its authority.