Garda murderer claims psychiatric evidence contradicted legal test for insanity

Stephen Silver has appealed his conviction for the murder of Garda Colm Horkan, shot eleven times with his own service weapon in Castlerea, County Roscommon, on 17 June 2020. Silver's legal team contends that psychiatric evidence presented at trial by the State contradicted the proper legal test for insanity under the Criminal Law (Insanity) Act 2006. Defence counsel argued that Silver's mental illness substantially diminished his responsibility for the killing, warranting a manslaughter verdict. Prosecution expert Professor Harry Kennedy testified that Silver demonstrated functioning mental capacity through purposeful actions with specific intent. The defence countered that the ability to form intent does not exclude a finding of diminished responsibility due to mental illness. The Director of Public Prosecutions' counsel maintained that the trial judge's charge to the jury was entirely appropriate. The Central Criminal Court panel, comprising Justices John Edwards, Patrick McCarthy, and Isobel Kennedy, reserved judgment. Silver, aged 49 from Foxford, County Mayo, was convicted in April 2023 and sentenced to life imprisonment with a minimum forty-year term.