Norfolk Constabulary has made the decision to formally close its investigation into the hacking of online data from the Climate Research Centre (CRU) at the University of East Anglia (UEA) in Norwich.

The decision follows a comprehensive investigation by the force’s Major Investigation Team, supported by a number of national specialist services, and is informed by a statutory deadline on criminal proceedings.

While no criminal proceedings will be instigated, the investigation has concluded that the data breach was the result of a ‘sophisticated and carefully orchestrated attack on the CRU’s data files, carried out remotely via the Internet’.

Senior Investigating Officer, Detective Superintendent Julian Gregory, said: “Despite detailed and comprehensive enquiries, supported by experts in this field, the complex nature of this investigation means that we do not have a realistic prospect of identifying the offender or offenders and launching criminal proceedings within the time constraints imposed by law.

“The international dimension of investigating the World Wide Web especially has proved extremely challenging.

“However, as a result of our enquiries, we can say that the data breach was the result of a sophisticated and carefully orchestrated attack on the CRU’s data files, carried out remotely via the Internet. The offenders used methods common in unlawful internet activity to obstruct enquiries.

“There is no evidence to suggest that anyone working at or associated with the University of East Anglia was involved in the crime.”

The security breach was reported to Norfolk Constabulary on 20 November 2009, following publication of CRU data on the internet from 17 November onwards.

An investigation was launched by the joint Norfolk and Suffolk Major Investigation Team, led by Det Supt Gregory, with some support from the The Met’s Counter Terrorism Command, the National Domestic Extremism Team and the Police Central e-crime Unit, along with consultants in online security and investigation.

The investigation, code-named Operation Cabin, focused on unauthorized access to computer material, an offence under the Computer Misuse Act 1990, which has a three year limit on proceedings from the commission of the original offence. It has been concluded by Norfolk Constabulary, in consultation with The Met, that due to outstanding enquiries this is now an unrealistic prospect.

Norfolk Assistant Chief Constable Charlie Hall, Protective Services lead, said: “Online crime is a global issue. While law enforcement agencies continue to develop our response to emerging threats, it falls upon individuals and organisations to be alert to this and and take steps to mitigate risk as far as is practicable.”

Prof Edward Acton, Vice-Chancellor of the University of East Anglia, and Prof Phil Jones, Research Director of the Climatic Research Unit, said in a joint statement that though they weren't happy with the result of the investigation, they were grateful to police for their hard work.

"We are naturally disappointed that those responsible for this crime have not been caught and brought to justice. We are very grateful to Norfolk Constabulary for their sustained effort over the last two-and-a-half years, and appreciate the difficulty of devoting continued resources to such a complex international investigation," Prof. Acton said. "Clearly the perpetrators were highly sophisticated and covered their tracks extremely carefully."

“The misinformation and conspiracy theories circulating following the publication of the stolen emails – including the theory that the hacker was a disgruntled UEA employee - did real harm to public perceptions about the dangers of climate change," he added. "The results of the independent inquiries and recent scientific studies have vindicated our scientists, who have returned to their important task of providing the best possible scientific information on this globally critical issue.”

“I would like to thank the police for their work on this difficult investigation and also for the personal support they offered me," Prof Jones said. "I am obviously disappointed that no-one has been prosecuted for this crime but hope today’s announcement will draw a line under the stressful events of the last two and half years. My colleagues and I remain committed to the research CRU undertakes to illuminate the globally important issue of climate change.”