IT WAS a schoolhouse of heinous abuse. Five teachers from St John's National School in Sligo town have been convicted of indecently assaulting young boys over three decades. Three of them were Marist brothers, two were lay teachers, and many of the abusers were assaulting the children at the same time. Hundreds of children were affected by the men's crimes, systematically perpetrated from the 1960s to the 1980s.

"If there was a smell of alcohol off him in the morning, you knew you were in trouble," one of Christopher Cosgrove's victims told the Sunday Tribune. The former Marist brother was sentenced to 12 months' imprisonment two weeks ago after being convicted of 35 charges of sexual abuse against four young boys between 1968 and 1977. It was the fourth time he had stood trial on the same charges, having been convicted and jailed in 2005, but this conviction was later ruled unsafe and a retrial ordered. He walked free from Dublin Circuit Criminal Court because of time already served in prison.

"He used to pick on the cute-looking boys and the ones who he thought were weaker and wouldn't try to stop him. It used to happen at his desk. He would call you up on the pretence of going over your homework if it was wrong. You'd often get called up if you'd been crying as well. He'd start with his hands around your waist. Then he'd go into your short trousers and around by your backside and into your underpants. That's my recollection. I saw it happen to other boys as well as experienced it myself."

Unlike in primary schools today, where teachers are assigned to a different class of pupils each year, the 60-plus students in Cosgrove's class were taught by him for four years. "Four, long hard years. It gave him an opportunity to really get to know us, to groom us, to pick out the weak boys and the ones he liked," adds the now middle-aged man, who became a chronic alcoholic because of the abuse he suffered at the hands of the former religious brother. He has since recovered from alcoholism.

'A vivid recollection'

"I saw it happening to other boys too. I have a vivid recollection of looking up from my desk once even though we weren't allowed look up. I saw him with another boy at his desk. This boy was one of the best students, he had no need to be up there. He had his hands on the boy and was also moving his own hands furiously under the desk. I know now that he was masturbating himself.

"We didn't know what was happening to us. We had no idea what sex was. But we became sexualised at a very early age because of that man. It was a reign of complete terror. Aside from the sexual abuse, he was also physically violent beyond belief."

The children used to talk in the playground about Brother Christopher. They knew what he did to the boys when he brought them to his desk was wrong. But, as children, they had no real comprehension of his actions. They simply called him a "steamer", a derogatory term for a gay man.

"When I was around nine or 10, I began to realise it wasn't right. But I didn't understand. I didn't know if he was dirty or I was dirty. I remember one of the tougher boys said to one of the other boys he used to always abuse, 'When you go back into that classroom you tell him to stop doing that to you or I'll beat the shit out of you.' The boy went in to Cosgrove and repeated what the other lad told him. I'll never forget the beating that Cosgrave gave the tougher boy. He beat him to within an inch of his life. That child left the school that day and never came back. That was the end of his education."

Cosgrove's sentencing two weeks ago has brought to a close a horrific chapter of abuse at St John's National School. Justice for his victims was frustrated by judicial reviews, appeals and retrials. Cosgrove's conviction brings to five the number of men who sexually assaulted children at the school. The concentration of abusers at the seemingly unremarkable school in the northwest is disturbing. At best, it was an unfortunate coincidence. At worst, some of the men were facilitating their fellow abusers in crimes against children. The four other men convicted of sex abuse are two other former Marist brothers, Martin Meaney and Peter White, as well as lay teachers Patrick Curran and Michael Cunnane. "There has been no evidence of a paedophile ring," according to a senior garda source. "But that many of the men were teaching there at the same time is a concern."

Far-reaching investigation

It was 1995 when Paul Gordon first went to gardaí to report the sexual abuse he suffered at the school many years previously. If he had not told gardaí what was happening, it's quite possible that the litany of abuse would have remained hidden. Detectives investigated his initial complaint but the DPP directed that no-one face charges. But a local nun, as well as Gordon's solicitor, helped him make another complaint in 1999 and a second, more extensive, investigation was launched. Martin Meaney was later convicted of sexually assaulting Gordon. The second garda investigation was far-reaching. Hundreds of students were interviewed. It led to the eventual successful prosecution of the five men.

"When the gardaí knocked at my door in 1999, the first thing I said to them was, 'What took you so long?'" added the man who spoke on condition of anonymity.

While Cosgrove was sentenced for sexually abusing him, he does not feel that he has gotten justice. The former Marist brother, who is now married to a former nun, was originally jailed in 2005 for eight years for the abuse of children but this was overturned by the court of criminal appeal because of an issue with the judge's charge to the jury.

The second trial collapsed because one of the witnesses mentioned during testimony that there had been a previous trial. The third trial also had to be abandoned when counsel for the prosecution was forced to withdraw for ethical reasons. Then – finally – two weeks ago, a jury for the second time found the 66-year-old unanimously guilty of 35 charges of sexual abuse against four young boys. "This has been going on for 10 years. I have given up a decade of my life over this as well as my childhood. No, I do not feel vindicated. The gardaí involved were brilliant but the court system failed us," said the man, who gave evidence against Cosgrove. "If that jury a couple of weeks ago came back and said 'not guilty' I don't think I could have coped."

Victims of sexual abuse deal with the trauma in different ways. Another boy who Cosgrove abused at the school had no recollection of what happened to him until gardaí came to talk to him about his schooldays in 1999 and it all came rushing back to him. "I put it out of my mind and simply did not think about those days," he told the Sunday Tribune. "He is a manipulative, calculating man. What happened affected my life. I didn't have a serious relationship until I was in my 30s. The four other men have made some admissions about abusing the boys. But Christopher never has and he never will. He took away our innocence."

St John's National School: The Abusers

Peter White (Brother Agnellus)

Sentence: three years in prison

In June 2005, Peter White (74) of Celbridge Abbey, Celbridge, Co Kildare, was sentenced to three years in prison after pleading guilty to eight sample charges of indecent assault on two boys, in the 1970s. His trial was told that he had inflicted "unfathomable torture" on the two small boys entrusted to his care. White followed the boys into the school toilets where he indecently assaulted them. Trial judge Miriam Reynolds said that he had used his cunning and his position as a teacher to terrorise these children in the classroom, where they should have felt protected and safe.

Patrick Curran (lay teacher)

Sentence: 12 years in prison, later reduced to nine on appeal

In July 2005, Patrick Curran was found guilty at Dublin Circuit Criminal Court of indecently assaulting nine boys he taught at the Sligo school between 1966 and 1984. Described by the trial judge as a "determined paedophile", Curran taught at St John's National School from July 1966 until he was asked to leave when the allegations came to light in 1999. Curran had denied an initial 237 counts of the indecent assault of 10 boys between September 1966 and June 1984. At his trial, he described himself as a "gay person" with a sexual preference for old people over the age of 65.

Michael Cunnane (lay teacher)

Sentence: three years suspended

In October 1999, retired teacher Michael Cunnane received a three-year suspended sentence after pleading guilty to 11 counts of indecently assaulting three boys between 1974 and 1981. In May 2001, the same teacher was back before the courts. That time, he received another suspended three-year sentence after admitting further counts of indecent assaults against five boys. The abuse occurred under the pretence of giving horseriding lessons.

Martin MeAney (Brother Gregory)

Sentence: Two years in prison

In January 2008, Martin Meaney received a two-year jail sentence on five sample counts of indecent assault against one victim, Paul Gordon. Meaney admitted he had selected his victim carefully because of his impoverished background and because he appeared weak and hungry-looking. He groomed him for weeks before the abuse began. He took advantage of his then seven-year-old victim's need for attention and kept him back after school pretending it was to give him music lessons.

Christopher Cosgrove (Brother Christopher)

Sentence: 12 months

Convicted and then sentenced in May 2010 of 35 charges of sexual abuse against four young boys between 1968 and 1977. He stood trial on four occasions on charges of abuse at the Sligo school. He was initially found guilty in Sligo Circuit Criminal Court. But that conviction was later overturned in the Court of Criminal Appeal. Two further trials for the same crimes collapsed. He denied all the charges. He walked free from court two weeks ago because of time already served.