A man told gardaí he slashed the neck of a fellow resident at an addiction treatment centre because of “thoughts and images” in his head that his family would be murdered, a court heard on Tuesday. Sean Beumer (29) pleaded “not guilty by reason of insanity” on the opening day of his trial to charges of assaulting the victim causing him harm and to producing a improvised “shiv” or knife during the attack. The trial at Limerick Circuit Criminal Court heard that the victim told gardaí he was attacked from behind by Mr Beumer and had his neck “slashed”. Mr Beumer, with an address at Edenmore Crescent, Raheny, Dublin 5, told gardaí the “thoughts” in his head had “brainwashed” him into erroneously believing that he and his family would be murdered, and that if he hurt another person he would save himself and his family from harm's way. At the time Mr Beumer was residing at Cuan Mhuire addiction treatment centre in Bruree, Co Limerick, where he and the victim were participating in an alcohol detox programme. The trial, before Judge Colin Daly and a jury of seven men and five women, heard that Mr Beumer’s previously prescribed medications were “discontinued” in line with normal detox protocols at the centre. Mr Beumer had been admitted to the alcohol detox programme on November 29th, 2019, and the attack on the victim occurred 15 days later on December 13th. Sergeant Larkin agreed with the accused’s barrister, senior counsel Lorcan Connolly, who said that Mr Beumer told gardaí that the urge to harm someone in order to relieve his bad thoughts was “building” throughout the days he was off his medication “and he cracked”. The attack occurred at the smoking area of the treatment centre at around 1.30am on the morning in question. After his arrest Mr Beumer told gardaí: “I went into the smoking room and put him [the victim] into a sleeper hold and tried to cut his face.” “It was all building up after 10 days, all these thoughts, I just exploded,” Mr Beumer said. Mr Beumer told gardaí he was “relived” when he carried out the attack , although he said his intention was to “cut” the man’s “face” but he “couldn’t see in the dark”. He told gardaí that after the attack he put his bloodied hoody top in a bin. Sergeant Larkin told the court that after he arrived at the scene later on the morning he found Mr Beumer in his room kneeling and praying by his bed. Sergeant Larkin agreed with Mr Connolly that the accused had expressed remorse and he was cooperative with the Garda investigation. The court heard Mr Beumer told gardaí the attack was “not personal”. “He [the victim] was the only [resident] awake, it was not personal, I was doing it to save my family,” Mr Beumer told gardai. “I was brainwashed into thinking it was the right thing to do.” “I was ill, sick, depressed, I was asking to leave and they said ‘No’, I didn’t know what else to do,” Mr Beamer told gardaí. When asked if he had wanted to kill the victim, Mr Beumer told gardaí: “No, just hurt him”. “Yeah I did it, I’m admitting to it because I don't want it hanging over me.” “I’m so sorry for what i done, I was pressurised into doing it.” Mr Beumer claimed that another resident, whose name he couldn't remember, had shown him how to make a weapon by fixing unguarded razors to the plastic handle of a disposable razor. The court heard that the victim and the accused had become friends while resident at the centre and they had been playing checkers together in Mr Beumer’s room moments before the attack. CCTV footage played in court showed Mr Beumer following the victim out of the room towards the smoking area. The footage showed the victim later with blood around his neck approaching a nurse at the centre. Sergeant Larkin said one of the victim’s slash wounds ran across the length of his neck. Sergeant Larkin said one of the centre’s staff members, Sr Agnes Fitzgerald, had “innocently” cleaned up some of the blood at the scene as she was “not forensically aware”. Sr Fitzgerald told gardaí that she handed the weapon used in the attack to gardai after it was found by a volunteer staff member Michael Barrett. A forensic scientist attached to the State science laboratory described the weapon as a “shiv” or makeshift knife. Michael Barrett told gardaí the shiv “was like something you’d see in the movies” and that he saw “a lot of blood” near the scene leading towards the victim’s room, which was situated two doors from Mr Beumer’s room. Mr Barrett said he saw “cuts to [the victim’s] neck” and that Mr Beumer was “praying and kneeling at his bed” before going for “a shower”. A staff nurse who was on duty on the night in question told gardai that the victim approached her bleeding from his neck and hand. The nurse said she “applied pressure” to the victim’s wounds and brought hm to his room as Gardai and an ambulance were alerted. Garda David Hggins, of Bruff station, said he found the victim had suffered “a slashed throat” and he had taken a formal statement from the man and secured his clothing for forensic tests. A medical report sustained three lacerations to his neck, including one which was seven niches in length, as well as a laceration to his hand. The victim told gardaí a man he believed to be Mr Beumer, whom he called “the Dub”, had “slashed open my neck”. The man said he had “no idea why the attack happened”. “I got choked out from behind. When I woke I saw blood dripping everywhere. I remember being choked and being told ‘go to sleep’,” the man told gardai. Blood samples taken from a hoody top worn by Mr Beumer when he said he attacked the victim were forensically examined and found to be a match for the victim’s DNA. The trial continues on Wednesday.