The new documentary Casting JonBenét has caused quite a stir ahead of its launch on Netflix this April. Billed as a "stylised exploration of the world's most sensation child-murder case," the Kitty Green directed film reflects on one of the talked-about child murder mysteries in US history.

Following the huge success of television specials of the JonBenét Ramsey murder case on CBS and Investigation Discovery, along with a Lifetime movie, Netflix is set to deliver another exploration into the unsolved case.

Now, a new trailer for the forthcoming documentary has been released and gives viewers a taste of what to expect. Australian director Green calls in actors, some professional and some amateur, from the Boulder area of Colorado to audition for the roles of JonBenét, her now-deceased mother Patsy, father John and brother Burke – who most recently appeared on the Dr Phil show to discuss his sister's death in late 2016.

In the trailer, the actors are asked to offer their own theories and suspicions about what happened on the fateful night of JonBenét's disappearance as part of the audition process, along with why the case still resonates with them two decades on.

The documentary – which has been described as "richly moving" by one critic – has been acquired by Netflix, who now have worldwide rights to it in advance of its Sundance screening. It will begin offering the film on the streaming service on 28 April.

On the fateful afternoon of December 26, 1996, six-year-old child beauty queen JonBenét Ramsey was found dead in the basement of her family home with a nylon cord around her neck and her wrists tied above her head.

Her mouth was covered by duct tape and the results of the autopsy revealed that she had been killed by strangulation and a skull fracture.

The official cause of death was asphyxiation due to strangulation associated with craniocerebral trauma – and there was no evidence of conventional rape.

Her parents John and Patsy, and brother Burke, were cleared of her murder in 2008 following new DNA evidence from the victim's underwear that didn't match theirs.

The three members of the family were the only ones at the home in Boulder, Colorado, on the day of JonBenét's disappearance.