The tragedies and brutalities of others form the substance of Laura Richards’s professional life. But unlike other police officers, whose job it is to catch the perpetrators of crimes, Ms Richards works to ensure that future criminals never get the chance to commit them.

She is the head of analysis of the Metropolitan Police’s Homicide Prevention Unit, whose task it is to detect crimes before they are committed. If it sounds futuristic, an echo of the Tom Cruise film Minority Report — in which psychics predict murders so that the perpetrators can be arrested first — it isn’t. This is a unit that uses the best psychological and criminological advances to identify the killers of tomorrow from the lesser criminals of today.

Criminal psychology now accepts that crime, violent crime in particular, is preventable. The warning signs are there. The man who beats up his wife is not just a violent husband but a killer in the making. His violence may not be restricted to within his own four walls but could affect the wider community. The man who indecently exposes himself to women may be the rapist of tomorrow. The man who commits minor sexual assaults may well move on to crimes of a far more serious nature.

The theory that drives Ms Richards is the knowledge that murders are preventable. What you have to do, she says, is learn to read the warning signs.

She and her team of analysts, who work within the newly formed Violent Crime Directorate, are building up psychological profiles of likely offenders in order to map out patterns of criminal behaviour.

They gather complaints about an individual from former partners, mental health workers or sex workers and file them as a single source, using the information to identify who is most likely to graduate from lesser offences to serious violent crime.

The aim is twofold: the intelligence can be used by police investigating a crime that has already taken place. But, more controversially, Ms Richards hopes that it will help to identify murderers in the making and allow police or support agencies to intervene — for example through monitoring, social services or mental-health referrals — before a crime is committed.

“It is gritty stuff, and it is hard work, but it is important,” she says. She rattles through a list of names. “They all slipped off the radar. Why? People do some evil things and you are never going to stop all of them. But what I have a problem with is when the professionals sit by and let it happen. That is when I become a pain in the side of the authorities. I am not political. I am not in this for rank. That’s what makes me a dangerous person. That’s what gets me fired up.”

Ms Richards, 31, has proved herself one of Scotland Yard’s rising stars. After gaining qualifications in forensic and legal psychology, she trained with the FBI before joining the Met. After a brief interlude as a consultant at the Home Office, combating domestic violence, she moved to her present job, advising senior officers on crimes such as sexual violence and honour killings. Between attending crime scenes, she studies for a PhD in criminological psychology.

Ms Richards has given expert evidence against murderers and rapists. She has twice investigated cases of cannibalism where internal organs were cooked and eaten.

Central to her theories about crime is the belief that the domestic abuser and opportunistic killer — the bogeyman in the bushes — are potentially the same person. The theory is familiar among social scientists, but has been slow to develop in police culture.

“Offenders do not just wake up one morning and decide out of the blue to kill somebody,” she said. “Ian Huntley did not just start with Holly and Jessica. There is a continuum. People who are violent to strangers have usually shown violence towards their partners or others close to them. Because they start raping within four walls or in a relationship does not mean they won’t carry on outside the home. To separate the categories is absolutely false.”

Police working on an apparently random attack by a stranger have in the past been too quick to eliminate individuals with a history of lesser crime, she said. “We all want offenders to have two heads, and look absolutely recognisable because otherwise we don’t know how to spot them.

“But they can be sufficiently charming and plausible; they can seem like ordinary individuals,” she said.

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