Sherlock and "The Hobbit" star Martin Freeman is set to be the lead character in a new real-life detective series for ITV studios.

But, unlike Sherlock, the ITV drama "A Confession" is based on a true story: It's the story of a police officer whose career was ended after he caught a murderer using controversial methods.

47-year-old Emmy and BAFTA-winning actor Freeman will play former detective superintendent Steve Fulcher, whose career was destroyed when he was accused of deliberately breaking the police procedural rules in order to arrest a man he knew to be a double-killer.

Catching a killer

Fulcher was the lead Wiltshire Police detective investigating the disappearance of 22-year-old Sian O’Callaghan in 2011.

The young woman disappeared after leaving a nightclub in Swindon, leaving her distraught partner to frantically text her in the middle of the night and eventually contact the police. The dedicated team of officers scoured CCTV and organised a search, believing the young woman was still alive.

Eventually, the investigation culminated in the arrest of 50-year-old taxi driver Christopher Halliwell - who then went on to admit he had killed her - and that he had also stabbed to death prostitute Beck Godden eight years before. But Detective Superintendent Fulcher's methods for obtaining the confessions were brought into question, and the top cop resigned from the force under a cloud when it was found he had denied Halliwell access to a solicitor.

Cast and crew

Set in Wiltshire and the Home Counties, the six-part series will give Freeman a break from his Sherlock co-star Benedict Cumberbatch, with whom he is rumoured not to get on.

Instead, he will star alongside Oscar-nominated and BAFTA-winning actress Imelda Staunton - best known for "Vera Drake" and "Harry Potter" - and Downton Abbey‘s "Siobhan Finneran." Joe Absolom - best known for a comic role in ITV's "Doc Martin" - is set to play the killer, Christopher Halliwell.

Paul Andrew William - who directed ITV's celebrated drama "Broadchurch" - will direct all six episodes.

Screenwriter Jeff Pope wants the drama to question the way that the British police behave when someone goes missing. Pope won a BAFTA and was Oscar-nominated for his screenplay to 2013’s "Philomena." His latest Film is a biopic of Laurel and Hardy, titled "Stan & Ollie." It stars Steve Coogan and John C. Reilly.

Martin Freeman is also in Sky’s 10-part comedy Breeders and rumours that there will be the fifth series of Sherlock persist.