This time last year, a Minnesota woman named Diamond Reynolds made a chilling broadcast on Facebook Live, streaming the moments that immediately followed a police officer fatally shooting her partner Philando Castile during a traffic-stop. Reynolds’ four-year-old daughter was in the back seat of the car. If you saw the footage, which more than six million of us did, it was hard to forget it.

New Zealand-born, London-based artist Luke Willis Thompson was so moved by the story that he created a “sister image” in response, which is now on show at the Chisenhale Gallery in east London. In November last year the artist established a conversation with Reynolds and her lawyer, and invited her to collaborate with him on the artwork based on her story. The idea was to “break with the well-known image of Reynolds, caught in a moment of violence and distributed within a constant flow of news,” according to the Chisenhale.

The resulting silent portrait of Reynolds is shown as a vast single screen artwork in a otherwise eerily dark space, creating a potent and unnerving piece that gives agency to its subject; bestowing a power on her that was stripped as her story circulated in public. The piece, titled autoportrait, is shot on 35mm black and white film, and saw Thompson work with director of photography Mhairi-Clare Fitzpatrick, film and lighting technician Miranda Langevin, and project liaison Sara Cluggish.

Thompson produced the work as part of his Chisenhale Gallery Create Residency, and says it was directly informed by his move to London. “In the last ten or so years, I have been following riots that are triggered by the killing of a person of colour by police,” he says. “I felt arriving here, around the five-year anniversary of the 2011 riots, that there might be something new to say about that. Truthfully, I never got very far. Artistic research rarely means a straight line of enquiry.”

He continues: “Racialised life and death is something I have been talking about, and talking to, in my practice for some time… Last year I made the conscious decision to start watching the increasing number of videos of police violence that were circulating online. In this recent cycle of police violence, the terms of visibility changed with a wave of cell phone reportage. It was like every possible nightmare one could imagine might appear online.”

What struck him about Reynolds’ story in particular was that even in the depths of shock and grief, her video showed her as “so eloquent; she perfectly narrates what has happened, and who said what and when, which is crucial,” says Thompson.  “After Diamond’s video, I realised there was no more important conversation about the image than in these videos.”

Thompson went to meet Reynolds in February this year, in a tense but “moving” day overshadowed by the fact that everyone was aware her words could be used by the opposing side in the ongoing case involving the officer charged with Castile’s shooting. “In interviews, [the lawyer] Mr Rogers would often repeat the phrase ‘everything was already said in Diamond’s live streamed video’, so further testimony couldn’t be produced,” Thompson explains. That’s how the idea of a silent film was born.

Seeing the piece in a gallery setting has a profoundly disquieting effect, forcing the viewers to consider ideas around how people are represented, and the nature of grief. The odd mixture of stillness and movement makes Reynolds seem at once very real, but also slightly otherworldly. “There’s choreography to Diamond’s movements, which is about breaking the rhythm of the length of film and interrupting any pressure that might build during the filming process, which was not easy for her,” says Thompson.

He adds: “Diamond and I had many conversations about how she wanted to appear. We both had similar ideas; too many to cover in great detail here, but what stands out was our shared interest in an image’s life span. What Diamond wanted was less about the picture and more about the preservation of the film.”

Luke Willis Thompson, autoportrait, is on at the Chisenhale Gallery, 64 Chisenhale Road,
London E3 5QZ until 27 August 2017