Hou Xiaolin, foreground, talks about his girlfriend's disappearance, accompanied by the Zhang family in Urbana, Illinois in November, 2017. [Photo provided to China Daily]

Yet when Shi visited the family in August 2018 she saw only the debris of broken bowls and shattered dreams-the parents, blaming each other and themselves for encouraging their daughter to pursue a dream, fighting in front of the camera.

Reflecting on the intimacy with which she was allowed to film-the camera rolled when an inconsolable Ye lay in bed rubbing her hand against the woven straw mat she once shared with her daughter-Shi said that it took time for things to happen.

"At the very beginning, we were just two of many who had flocked to Champaign trying to get a slice of the story. But as we got to know more and more about Yingying, we decided to focus as much on how she lived as on how she died. We made sure the family understood that."

For Hou, Shi's perseverance is just as persuasive as her narrative approach."When she initially proposed the idea to me, I said no. As keen as we were to get public attention for the case, it would undoubtedly bring tremendous stress to us, especially the parents, when very often we needed to grieve in private. But she kept trying. Her passion, determination, and her experience of studying in the US alone after graduating from Peking University all reminded us of Yingying. We decided to help."

Yet most of the time Shi and Sun were with the Zhang family, they were not filming. "Let me put it this way: many times we visited them, we did so not for the purpose of filming," Sun says. "We would bring our camera and put it in a corner of the room. Other times the parents told us that they didn't want to be filmed and they still wanted to have us for dinner. We always obliged."

Asked what trait he thought Zhang had in common with her parents, Sun said, "Trusting".

Five months after her missing, a memorial at the site on the campus of UIUC where Zhang Yingying was last seen on June 9, 2017. [Photo provided to China Daily]

He's probably right. In one of her diary entries, Zhang wrote, "I told mom that there are both Americans and Chinese here-all extremely nice."

In retrospect, some footage was eerie. In one of the earliest scenes Shi captured, in the summer of 2017, Zhang's maternal aunt, on a random search on the street, pointed to a few dumpsters not far away and said, "I really want to fumble around in that... but I'm afraid we aren't allowed to..."

During Christensen's trial between June and July last year, the Zhang family were told that "after killing Yingying Zhang, Christensen placed her bodily remains into garbage bags in the dumpster immediately outside his apartment building", to quote Steve Beckett, the family's other lawyer.

"The contents of the dumpster were taken to a private landfill. It was determined that by the time Christensen's attorneys disclosed his statement to the federal authorities (in late 2018), the content of the dumpsters that contains Yingying's remains would have been covered by at least 30 feet of fill," Beckett told media after the trial.