The researchers say the results highlight the link between mental illness and violent crime. The idea of giving pills before a crime has been committed is likely to prove controversial Prof Seena Fazel of the University of Oxford’s Department of Psychiatry, who led the research, said: “This study raises the possibility that prescribed medications may provide a way to cut the risk of violent reoffending, as part of a wider package of support. The research also highlighted that medications seem to work beyond their immediate effects on symptoms.“We have shown that in a population with many mental health problems and high risks of reoffending, improving adherence and links with community health services may offer an effective way to improve outcomes for the individual prisoner and also public health and safety more broadly.”The researchers say the results highlight the link between mental illness and violent crime. Prescribing anti-psychotic medication to violent criminals when they leave prison could prevent around 1,500 serious crimes in Britain each year, a new study suggests.Although medicating prisoners on their release is controversial, the University of Oxford believes that it could dramatically cut the risk of violent offending.Researchers studied 22,275 prisoners who were released from jails in Sweden between 2005 and 2010, some of whom were prescribed drugs.There was a 42 per cent reduction in the rate of violent reoffending for those prescribed anti-psychotic drugs and 52 per cent reduction for those given medication for addictive disorders. Antidepressants were found to have no impact on reoffending rates.Around 3,000 serious violent crimes are committed by ex-prisoners in Britain each year but the study suggests the number could be halved if criminals were given drugs on their release. In the past drugs have been used in the past to ‘chemically castrate’ sexual offenders, but always after abuse has taken place.Many of the therapies used also have serious side effects such as breast growth, bone thinning, mood changes.But the new treatment would be more controversial because it would work before a crime has been committed. It is likely that any treatment would have to be on a voluntary basis.Earlier this year, experts in Sweden announced they are trialling a drug which can prevent paedophiles from abusing children.The medication degaralix stops the brain from making testosterone and can combat hyper-sexuality and aggression, turning off the need to seek out sexual contact with youngsters.Four men who rang a sexual offenders helpline have so far agreed to take part in the study.The new research was published in the Journal of the American Medical Association. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.