LONDON — British police have closed their three-year investigation into the theft of hundreds of climate science e-mails published to the Web, saying Wednesday there was no hope of finding any suspects behind the breach.

The theft caught researchers at the University of East Anglia’s Climatic Research Unit discussing ways to dodge right-to-know requests, keep opponents’ research out of peer-reviewed journals, and destroy data. The unguarded and occasionally unprofessional messages dented the reputation of several researchers and provided ammunition to skeptics of mainstream climate science, many of whom seized on the documents to claim that the threat of global warming was being overhyped.

Several overlapping inquiries have since vindicated the researchers’ science — if not their attitude — but the furor over the scandal dominated debate in the run-up to the crucial 2009 UN climate talks in Copenhagen.

Those talks ended in failure, and world leaders are still struggling to agree on a plan to impose caps on the emission of greenhouse gasses blamed for rising temperatures and melting ice caps.

A second leak, published to the Internet in 2011, came a week before similar climate talks in Durban, South Africa.

The local British police force investigating the breach said Wednesday that its officers had been struggling with the complexity of the attack and the three-year-long statute of limitations on Britain’s Computer Misuse Act.

Detective Chief Superintendent Julian Gregory of the Norfolk Constabulary said in a statement that his officers ‘‘do not have a realistic prospect of identifying the offender or offenders and launching criminal proceedings within the time constraints imposed by law.’’

The University of East Anglia said it was disappointed that no one had been caught but expressed gratitude for police’s help.