Updated Thursday, 27th May 2021, 10:46 am Robert Maudsley, now 67, spends his days locked away in a special underground cell under Wakefield Prison and is one of the country's longest-serving prisoners. Robert Maudsley, now 67, spends his days locked away in a special underground cell under Wakefield Prison and is one of the country's longest-serving prisoners. He killed four men, three of them fellow prison inmates, and has been the centre of a TV documentary, which aired last year. Maudsley, was put under the microscope for a new series of Making a Monster on the Crime and Investigation channel. It tells the story of how he came to be locked away in solitary confinement as one of the longest serving prisoners in British history and how he only became branded a serial killer whilst behind bars.