Dr Hill is a clinical psychologist who works as a profiler for the National Home Office, and frequently Bradfield police; he specialises in repeat violent offenders, and has come into contact with a number of serial killers throughout his turbulent career.

[1] He is occasionally implied as having a difficult relationship with his mother, an emotionally detached businesswoman who bore her son while she was still young and unmarried, at a time when such a thing was considered scandalous.

This approach often unsettles those around him and in the TV series, it isn't until Carol realises his worth in a practical setting that Bradfield CID embraces his ongoing assistance.

Within the novels, Tony has an established professional standing that earns him a place at the head of the National Profiling Task Force after he conducted the feasibility study that resulted in its formation.

Tony is also seen talking to these visions in an attempt to understand the crimes, and sometimes is even seen acting out the murders in his mind, anything from imagining stabbing a housewife to death in Sharp Compassion to beating and shooting a young man in the head in From the Defeated.

The question as to whether this is evidence of Tony's holistic genius in trying to understand the killer's motive or rather a more sinister psychological disturbance in his mind is left open to debate.