The Chinese consulate in Chicago is asking for a thorough investigation and swift justice in the case of a Chinese scholar, Zhang Yingying, 26, who is feared dead after an apparent kidnapping.

"We are shocked and heartbroken about what happened to Zhang," said Hong Lei, China's consul general in Chicago, adding that the feelings are shared by all Chinese people.

Brendt Christensen, 28, was formally charged in US federal court on Friday with kidnapping Zhang more than three weeks ago.