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Code of a Killer: deciphering the science

Posted by on April 14, 2015

By Professor David Hornby FRSB, Department of Molecular Biology and Biotechnology, University of Sheffield and Director of Research and Innovation, Liverpool Life Sciences UTC

Listen to Sir Alec Jeffreys being interviewed by Professor Alison Woollard FRSB at the RSB’s fundraising event in May 2016.

code_killerLast night I watched the concluding part of the ITV drama Code of a Killer, in which the Leicestershire police, led by DCS David Baker, (David Threlfall) sought the help of Alec Jeffreys (John Simm) to identify the rapist and murderer of two young girls in the early 1980s. I discussed the background to the science in an earlier blog post, but here I’ll talk about the scientific climate of technology and discovery surrounding molecular genetics in the late 1970s – early 80s.

Whilst methods were developed as long ago as 1974 for gene sequencing (thanks to Fred Sanger, Walter Gilbert and Allan Maxam), by 1982, molecular biologists had access to the genomes of just two bacteriophages (viruses that infect and replicate within a bacterium), along with the human mitochondrial genome (rather modest, by today’s standards!). And just in case you are too young to remember, finding a computer in a biology lab in the early 1980s, to analyse the sequences, was truly exceptional.

Working at the University of Leicester, the challenge that Alec Jeffreys faced, is one of the most fundamental aspects of genome science: on the one hand Darwinian evolution leads us to look for the similarities between genes in say mice and men. However, what is important in forensics (and paternity testing) are the elements in our genomes that make us different. These are the ‘stutters’ that are mentioned in the drama.

alec jeffreysThis picture shows Alec holding an autoradiograph revealing a series of DNA fragments which have been ‘highlighted’ through the use of a radioactive ‘probe’ designed to pick out DNA sequences complementary to the probe itself. In this way a sample from the scene of a crime can be unequivocally identified as belonging to the suspect, or (importantly) not.

The phenomenon of base pairing is a key component of the structure of DNA in which the bases G and C, and A and T, form ‘complementary’ pairs. So, if a fragment of DNA contains the sequence 5’GATTCCGGATTCA3′ (for example), then the complimentary probe sequence 5’TGAATCCCCGGAATC3′ would highlight it.

When Alec Jeffreys is shown in episode one, trying various probes to explore similarities and differences in genes, his focus on the seal myoglobin gene is shown because this is where he obtained the first high quality data in this way.

The second part of the drama begins with a press conference in which the police announce that their prime suspect has been excluded using genetic fingerprinting! There are few applications of science that have been so closely intertwined with the police and the legal profession. Ten years later, the US sports celebrity O.J. Simpson would be famously acquitted of the murder of his wife, following a high profile trial in which the evidence from genetic fingerprinting was dismissed, not because the science was suspect, but rather the ‘audit trail’ of sample collection and analysis was shown to be unreliable.

What I particularly liked about the second episode of Code of a Killer, is the recognition (and conviction) shown by DC Baker, that scientific evidence will provide the truth. Moreover, we mustn’t underestimate the importance of Alec Jeffreys’ success in communicating this so effectively to the police officer. The other parallel I like in the drama is that between the work of a principal scientist (PI) and that of a chief investigating officer (CIO): both involve the systematic collection, evaluation and rigorous testing of data. DC Baker’s leadership of his team will be a familiar tale to many PIs, as he navigates  through misleading results (false leads) and the challenges of funding and competing priorities (budgets and politics) to finally apprehend the killer (clone the gene!)

alec jeffreyThis production joins a handful of productions in which the profound value of science to society is showcased effectively. I also managed to get over the somewhat hackneyed references to the ‘committed scientist burning the midnight oil whilst neglecting his family’, in episode one. In fact, the scene in the second part, in which Alec Jeffreys persuades the community to submit to testing, by holding aloft his own genetic fingerprint alongside that of the killer, is a lovely moment that in my view, fully vindicates the pursuit and public support for ‘blue skies’ science.

If you have been fortunate enough to spend an evening chatting with Sir Alec, or have been present at one of his seminars, you will undoubtedly share my view (and that of the people of Leicester, who awarded him the Freemanship of the City in 1992) that he is not only an outstanding scientist but an exceptional human being. I will leave you with the thought that occurred to me when Alec Jeffreys aligned the autoradiograph taken from Colin Pitchfork and that recovered from a victim: Alec Jeffreys’ greatest legacy may be to human justice.

Listen to Sir Alec Jeffreys being interviewed by Professor Alison Woollard FRSB at the RSB’s fundraising event in May 2016.

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