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From news reports detailing the latest criminal conviction, to the glossy glamour of forensic investigation drama CSI, or the tawdry spectacle of daytime TV paternity tests, DNA fingerprinting has become a staple of popular science.

Indeed, if the success of an innovation can be measured by its impact on public consciousness, then the development of the technique by Leicester University’s Prof Sir Alec Jeffreys must surely be pretty near the top of the list.

Almost 25 years after its discovery, genetic profiling continues to grow in significance; it is the scientific bedrock for the UK’s national DNA database and, as the technology has caught up with the science, a range of devices are emerging that are enabling forensics specialists to analyse in hours what once took weeks.

The principle of DNA fingerprinting is that the differences between any living thing can be determined by the sequence of base pairs in a sequence. Rather than examine the many millions of pairs, the majority of which are identical, Jeffreys’ discovery uses repeating patterns in DNA to see whether two samples are from the same individual, or related individuals.

Jeffreys’s breakthrough came at Leicester, at a time he remembers precisely as 9.05am on Monday, 10 September 1984. An X-ray examination of the DNA of a colleague and his family showed remarkable similarities. Since then, Jeffreys’ discovery has been extensively used in forensic science, paternity testing and identifying family links in immigration disputes.

Articulate and personable, Jeffreys is an advocate of science and technology research, and is still is amazed at the impact of his innovation. ‘It’s gone way beyond anything I could have imagined,’ he said. ‘Nobody really knows how many people’s lives have been touched by DNA analysis and through DNA fingerprinting technologies — the numbers start at 20 million.

‘We’re now living in a world where just looking at convictions, there are 12 million criminals logged on worldwide databases with the number going up rapidly. Add to that the innocent people released from jail thanks to DNA testing, the large number of immigrant families broken up through disputes where we can establish family relationships and bring them back together, and paternity tests which must be well into the millions by now. Every one of these tests is a drama for those involved.’

Jeffreys said one of the biggest changes in recent years is the improvement in the technology that is used to create and analyse DNA fingerprints. In the early days, it could take weeks to go from a crime-scene sample to a DNA profile. Today, time and cost have been greatly reduced and forensic scientists are able to carry out laboratory work at the crime scene.

One particularly exciting area is the development of handheld testing devices that promise to eliminate the delays and expense involved in transporting DNA samples to a central analysis facility and produce results in less than an hour.

‘Nowadays if you pull all the stops out you get results in about two hours,’ said Jeffreys. ‘It would be good to get it quicker, and I see no theoretical reason why instant, real-time DNA identification can’t be done — but not with current technology.’ Jeffreys can even foresee a scenario in which instantaneous testing could ultimately lead to the development of DNA PINs that could be used to replace passports or credit cards.

Nevertheless, the underlying principle is the same. ‘The basic concept is to cherry-pick within the human genome looking for bits of DNA that are excellently variable from one person to another, then use that to build a basis for biological identification,’ he said. ‘That concept has stayed the same, but the way you access and type these variable regions has shifted over the years. It has made the technology more robust, but it hasn’t changed the discriminating power at all.’

Jeffreys has now left the business of developing and refining the technology to the experts — and has moved on to other fundamental scientific questions.

‘I’ve gone straight back to my roots as a basic biologist to ask some very basic questions, such as human DNA is tremendously variable, where is that variation coming from? What processes are generating it, how fast is it being generated, what about the environment we live in and does that affect the stability of our DNA? These are basic scientific applications that have no practical application, and I make no apologies for that.’

Speaking of the need for funding and the fact that many research scientists have to teach rather than further their research, Jeffreys said: ‘Technological innovations tend to come from new science in a very unpredictable fashion. Antibiotics are a very good case in point. Would you ever have funded Fleming for leaving his window open and his Petri dishes unguarded in the hope that he might find antibiotics? One important aspect from the work we’ve done is the fundamental importance of keeping a research base going. It’s creating the new things you don’t know you need.’

Jeffreys takes pride in the fact that for many people DNA is an easily-recognised element of forensic investigations. ‘Almost by accident, we’ve managed to turn DNA into an entertainment, something people are interested in. We can use forensics and criminal investigations to inform people about really quite basic issues, like what human genetics is, how it works and what it can tell us.’

Though a lot of the science covered in programmes like CSI is accurate, Jeffreys sees two problems with the popularisation of forensic science. ‘It’s so exciting, it turns kids on to science as a vibrant subject. The downside of that is they all want to become forensic scientists and there are not enough jobs in the world.

‘The other “CSI phenomenon” is it turns every man, woman and child into a forensic expert, and there have been situations in the US where juries reject the DNA evidence presented by the police as it’s not how they’ve seen it done on CSI.’

The shock paternity revelations on daytime television disturb Jeffreys more. ‘That makes me cringe,’ he said. ‘Every one of these cases is a human drama, and I think if you’re having that kind of information, at the very least you need proper counselling. This is not the stuff of prime-time TV.’

Jeffreys believes that in court cases, forensic evidence is explained well to jurors, but in some cases the defence will blind or bore the jury with science, prompting them to reject the evidence. ‘You need an additional layer, which takes the scientific enquiry to an initial hearing to verify the science has been carried out correctly and the results in the case are reliable.

‘To ask juries to decide upon weighty matters like statistics and molecular genetics and population biology and so on is inappropriate and unfair.’

Jeffreys is on record as saying he is against a UK-wide DNA database. ‘It’s wholly inappropriate,’ he said. ‘The future is going to involve major discussions about just what you do with these databases, how all-encompassing they are, what do you do with the information, do you store the DNA fingerprints of everybody? What about storing after death to inform future generations?’

He also believes there are major issues about the potential future of DNA identikit, which has the potential to extract information about the physical appearance of the person.

‘There’s a whole raft of socio- political and ethical issues that have barely been touched upon yet,’ he said. ‘Ultimately it has got to be society and politics that dictates what police can and cannot do with DNA — and that debate has not yet finished.’

Jeffreys regards his field of science with the same wonder as his first chemistry set at the age of 14. ‘Since 1984, when I first had the idea of DNA-based biological identification, it has been an incredible journey, one that’s gone 10 times faster and 100 times further than I thought it would go,’ he said. ‘My proudest achievement is my scientific baby from 24 years ago growing up and turning into an extraordinary creature, charging round the world, causing all sorts of chaos, but really helping people’s lives in a very positive way.’