(CBS) – Federal agents have arrested a suspect in the kidnapping of a Chinese scholar at the University of Illinois and indicated they don’t think the victim is alive.

Brendt Christensen, 27, of Champaign was arrested Friday on a criminal complaint that charges him with kidnapping Yingying Zhang on June 9, the U.S. Attorney’s office in Urbana announced. Zhang was last seen getting into a black Saturn at the downstate campus.

Yingying Zhang (FBI)

An affidavit says under surveillance, agents overhead Christensen “explaining that he kidnapped Zhang,” authorities said.

“Based on this, and other facts uncovered during the investigation of this matter, law enforcement agents believe that Ms. Zhang is no longer alive,” federal prosecutors said in a news release.

Christensen told investigators he saw Zhang looking lost and offered her a ride. He initially told the FBI he let her out a few blocks away.

But investigators say they later found evidence on his cellphone that he had visited an online forum with topics including “perfect abduction fantasy” and “planning a kidnapping.”

Christensen was expected to appear in court Monday, authorities said.