20/20 Full Episodes
20/20 RECENT REPORTS
In 2017, Brendt Christensen was interrogated by the FBI in Champaign, Illinois.
"I'm angry that it could've been prevented," Mike Christensen said.
Zhang's family visits her memorial during the trial for her murder, two years after her disappearance. Xiaolin Hou, Zhang's boyfriend, said "The only way to find some relief ... is to find her."
Brendt Christensen is accused of killing Yingying Zhang in June 2017.