The suspect in the kidnapping of a University of Illinois scholar from China marched in a vigil for the victim a day before his arrest last week, federal prosecutors said Wednesday, adding that he also spoke about what makes an ideal victim and talked about how she fought and resisted.

The new details surrounding 26-year-old Yingying Zhang’s June 9 disappearance arose at a detention hearing for Brendt Christensen in U.S. District Court in Urbana, not far from the central Illinois school, a statement from the U.S. attorney’s office in Springfield said.

U.S. Magistrate Judge Eric Long ordered that Christensen, 28, remain jailed pending trial. Long said the recent graduate student at the university’s physics department poses a danger to the community and is a flight risk.

Last Thursday, which was the day before Christensen was arrested, hundreds of people gathered on campus and walked to a street where Zhang was last seen. Prosecutors say Christensen was in the vigil group. Zhang’s father, a factory driver who traveled to Illinois from China for the search, also attended.

Prosecutors haven’t explained who Christensen spoke to about abducting Zhang, including whether someone close to him secretly recorded him. They divulged the details at Wednesday’s hearing to back their contention that Christensen is too dangerous to release.

The U.S. attorney’s office statement said Christensen “made a threat to another person to whom he made incriminating statements.” The statement didn’t elaborate.

It added that Christensen “has made statements about the characteristics of the ideal victim” and that he also told to an unnamed person that Zhang “fought and resisted” as he abducted her. It didn’t go into details.

Christensen’s lawyer, Evan Bruno, didn’t immediately return a message seeking comment Wednesday.

Zhang was abducted on her way to sign an apartment lease off campus in Urbana. Christensen allegedly lured her into his car after she got off one bus and tried to flag down another bus. In April, his phone was allegedly used to view a forum called “Abduction 101” online.

Christensen earned a master’s degree in physics from the University of Illinois in May and lived in nearby Champaign. He previously lived in Stevens Point, Wis.

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