Hundreds of people gathered outside a federal courthouse on Monday as the suspect in the kidnapping of a Chinese scholar at the University of Illinois made his first court appearance since he was arrested last week.

During the nine-minute hearing, 28-year-old Brendt Christiansen did not speak other than to acknowledge to the federal judge that he understood his rights. US magistrate Eric Long ordered Christiansen held without bond in the kidnapping of Yingying Zhang. Authorities say facts in the case indicate the 26-year-old Zhang is dead, although her body hasn’t been found.

Long ordered Christiansen to return to the court in Urbana on Wednesday to determine bond. A preliminary hearing was set for 14 July, but that would be waived if a grand jury returns an indictment before then. The federal kidnapping charge carries a maximum sentence of life in prison, according to a spokeswoman for the US Attorney’s office. The (Champaign) News-Gazette reported that about 45 people attended the hearing Monday morning, with another crowd in the courthouse lobby and yet more people across the street, many chanting “Justice for Yingying”.

After the hearing, Christiansen’s attorney, Evan Bruno, said he has talked to Christiansen a few times but that “this case is very young and we haven’t had a really full opportunity to develop everything yet”.

Bruno asked the public to “be patient, to keep an open mind, wait till the evidence comes in”.

Zhang went missing on 9 June. Authorities announced that they believed she was abducted after viewing surveillance video showing her climbing into a vehicle. Authorities charged Christiansen on Friday after federal agents heard him tell someone that he had kidnapped Zhang and held her against her will.

Authorities say Zhang was trying to hurry to an apartment to sign a lease and had been unsuccessful in flagging down a bus when a car stopped. The video shows a woman authorities have said is Zhang climb into the vehicle in Urbana, 140 miles south-west of Chicago.

Since then, details have emerged about Christiansen, who had just earned a master’s degree in physics from the university this year, and the events leading up to Zhang’s disappearance.

Yingying Zhang seen in security camera footage the day of her disappearance. Photograph: Reuters

According to authorities, a website that hosted an “Abduction 101” forum linked Christiansen to the kidnapping of Zhang. According to the federal complaint, Christiansen’s phone was used on 19 April to visit that website, FetLife.com, including to view threads titled “Perfect abduction fantasy” and “planning a kidnapping”.

FetLife describes itself as “the Social Network for the BDSM, Fetish & Kinky Community”, stressing in online policy statements that it is a place for consenting adults to trade advice and images of themselves, and to arrange to meet. The acronym BDSM stands for bondage, dominance, sadism and masochism. Users provide their ages, genders and roles they wish to play but otherwise remain anonymous.

Established in 2008 by Canadian software developer John Baku, it now claims more than 5 million registered members.

FetLife prohibited hundreds of fetish categories this year after it was cited in several criminal cases, Baku said in a February online note to members. He said he wanted to reduce legal liability and risks to the wider community.

FetLife policy guidelines stress that any interaction online or in person must be between adults and consensual.

“FetLife’s community is ... open-minded and non-judgmental,” it says, adding, “Our number one priority is to create a fun and safe place for kinksters.”

Neither FetLife nor Baku responded to messages seeking comment.

Zhang’s father traveled from China to Illinois in June for the search. Zhang, who received her master’s degree in environmental engineering in China last year, was described by friends and family as bright and caring. She aspired to one day land a professorship so she could help her family financially.