The HBO Max dramatisation of 'The Staircase' has cast yet another major name for the series.

Toni Collette is joining 'The Staircase' as the woman who died under extremely mysterious circumstances, Kathleen Peterson. The HBO Max limited series is based on the 13 episode Netflix docuseries of the same name.

She'll be joining Colin Firth, who was previously cast as the man at the centre of the court case and husband to the victim, Michael Peterson.

This eight-episode dramatisation will be influenced by the original Netflix series, as well as the books and reports surrounding the court case of Michael. The author was accused of murdering his wife in 2001, for which he was sentenced to eight years in prison.

However, he has always claimed that his wife died after falling down the stairs at their home. There were many theories as to what happened, including a bizarre "Owl Theory". Police suspected he bludgeoned her to death and staged the scene to look like an accident. He was eventually convicted in 2003, before being granted a new trial eight years later. He was then sentenced to time already served, and was later freed.

The HBO Max series is written and executive produced by showrunners Antonio Campos ('The Devil All The Time') and Maggie Cohn ('American Crime Story').

Toni Collette has become one of the most prominent actors in Hollywood. From her first big break in 'Muriel's Wedding' in 1994, she's gone on to star in a number of successful and critically-acclaimed movies such as 'Little Miss Sunshine', 'The Hours', and 'Knives Out'. Her most recent release is currently streaming on Netflix, 'Stowaway'.