Over five million people watched the first episode of Des, the recent three-part ITV drama on Dennis Nilsen. Nilsen is believed to have strangled (or strangled, then drowned) up to 15 young men, many of them homeless. He was arrested in 1983 after committing his first murder in 1978, coming to the attention of the police when the drainage system outside his flat was blocked by human remains. 

This is the point at which the mini-series gets underway. It’s the story of an investigation in which the perpetrator is already known, with efforts directed towards identification of victims and securing a conviction when for a substantial period the only witness was Nilsen himself. The concluding episode focused on his trial and the far from straightforward question of Nilsen’s sanity in relation to legal and psychiatric definitions. 

At the centre, though, were the interactions between the three main protagonists: Detective Chief Inspector Peter Jay, who led the investigation, Brian Masters, author of the acclaimed book Killing for Company on which the mini- series was partly based, and Dennis (‘Des’) Nilsen himself. We see something of Jay’s and Masters’ burden of incredulity, uncertainty and revulsion. Through DCI Jay’s contacts with the remains of victims, with the families of victims, and with surviving victims we were not allowed to forget the tragic consequences of Nilsen’s acts.
The portrayals of these characters (David Tennant as Nilsen, Daniel Mays as Jay and Jason Watkins as Masters) were impressive. At the centre was David Tennant's nuanced portrayal, not of a monster but of a man who in many ways seemed superficially ordinary. He could be polite, open; seemingly compassionate and with a sense of justice; sardonic, suspicious, resentful and cold by turns; always articulate but with a hint of manipulation; tragically maladjusted and poorly understood even by himself. With our knowledge of what he has done, the effect is chilling and unsettlingly plausible. Many of his lines were recognisable from Masters' book, an authenticity that was matched by, for example, the reconstruction of Nilsen's rather squalid flat where a range of body parts were found in a number of locations.

Not that the series was graphic in its representations. It was commendably restrained and unsensational, avoiding tropes such as flashbacks to crimes or to the adversities of Nilsen's childhood, although apparently there have been some complaints about occasionally detailed allusions to Nilsen's crimes and his subsequent activities involving the bodies. Some viewers questioned the truly epic amount of cigarette smoking by the main characters. Personally, I’d have liked to have seen a fourth episode, on the years which followed the trial; this could have addressed interesting issues concerning adaptation to context and any developments in what Masters termed ‘comprehending’.

Overall, though, I found this mini-series to be well-constructed and economical in its evocation of a range of aspects of Nilsen's past. It also raised questions, often through juxtapositions and contextual details. These included the circumstances from which Nilsen drew most of his victims, the termination of the investigation on financial grounds when six victims were identified, not to mention a strong suggestion of homophobia. Some viewers may have been frustrated by the lack of ‘answers’, particularly with regard to Nilsen's motivations. Arguably this reflects our less than complete or unequivocal knowledge of Nilsen and, despite valuable research and insights, the limitations of current psychological perspectives on comprehending such issues. All too often media depictions and discussions of serial killers fail to go much beyond familiar stereotypes and tautologies. Posing questions and encouraging viewers to think may actually be more valuable. 

Dr Adrian Needs is a Principal Lecturer at the University of Portsmouth. This article was originally written for the British Psychological Society.