When a Catholic priest who taught at the Marist Regional College in Burnie, Tasmania, in the 1960s was sentenced to four years’ jail for child sex offences this week, it brought the number of past staff members who have been convicted of child sex offences to six.

Father Thomas Fulcher, 84, was sentenced at the supreme court in Hobart on Wednesday after pleading guilty to three counts of indecent assault against two boys which occurred at the school between 1964 and 1967.

He will be eligible for parole after two years.

Through most of the 1960s and 70s the school, which catered to around 150 boarding students and a similar number of day students, operated on a staff of 12 teachers.

Past students, including a former Tasmanian politician, have raised concerns that a number equivalent to half the teaching staff have since been convicted of child sex offences.

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At a brief sentencing hearing, Justice Helen Wood said Fulcher’s conduct was a “breach of trust at a profound level”.

“The children were innocent and so were the times,” she said.

Wood said Fulcher made one of the boys, who was abused at monthly to six-week intervals over two years, remove his pants before touching his genitals and making him perform a sex act in front of him.

He then performed confession with the boy, which Wood said “exclusively attributed the guilt of his own wrongdoing to an innocent victim”.

He indecently assaulted the second boy on one occasion by asking him to remove his pants to check if he was “normal” and then touching him.

The complainant

Richard, not his real name, was the second boy. He attended Marist College for three years, starting in the mid 1960s as a 15-year-old third-form high school student.

He went to visit Fulcher one evening during study time and Fulcher asked him to stand up and remove his pants.

He told police, in an allegation to which Fulcher has pleaded guilty, that Fulcher used his index finger to tap his penis until it became erect, at which point Fulcher told him he was “normal” and allowed him to leave his room.

Richard told Guardian Australia that as he returned to the dormitory that night, after lights out, another boy said: “Oh, you have been up to have a sex lec, have you?”

“I remember standing there frozen ... and then it became obvious to me that other people knew what sex lecs were,” he said.

Richard no longer lives in Tasmania and was not among a group of former Marist students who attended Fulcher’s sentencing hearing on Wednesday.

He said he was motivated to report after attending a school reunion five years ago and talking to a group of other former students.

“I remember sitting at a table and there was about eight people at the table and six of them had been touched by different priests,” he said. “I was shocked, and they were openly talking about it … I walked away pretty horrified.”

He made a statement to the royal commission, which was then referred to police. It was the first time he had spoken of the incident to anyone but his ex-wife. His father was a devout Catholic; even if he had wanted to tell him, which he said he didn’t, the disclosure would have been difficult.

“I know he trusted me but I don’t know if he would have believed me,” he said. “My dad said that the priests will tell you the facts of life when you go to school, he just didn’t know how far they’d take it.”

The other convictions

Fulcher is the sixth teacher associated with the college between the 1960s and 1980s to be charged with sexual abuse.

The first, and most high-profile, was former international cricket umpire and Marist College sports coach Stephen Grant Randell, who was found guilty in 1999 on 15 charges of indecent assault against nine girls when teaching at Marist Regional College between 1981 and 1982.

After Randell came the conviction against athletics coach Paul Ronald Goldsmith, who was jailed for six and a half years in 2005 after being convicted of 42 sex offences against 20 boys aged 13 to 16. He died in Tanzania in 2016, where he moved after completing his parole in 2012.

Former Catholic monsignor Philip Green, now dead, pleaded guilty in 2004 to indecently assaulting a former altar boy.

Gary Laurence Ferguson, who worked at the college in the 70s, received a cumulative sentence of at least five years in 2007 after two separate convictions but was not placed on the sex offenders’ register after the judge said he was “unlikely to reoffend”.

And Roger Michael Bellemore was sentenced to four years’ jail in 2008, with a non-parole period of two years, after being convicted of assaulting three school boarders between 1966 and 1971.

Fulcher did not retire until 2002, when a complaint was made against him to the church.

Former Greens state MP Paul O’Halloran attended Marist College in the 1960s, after winning a scholarship at the start of high school, when he was 12.

Fifty years later, as the member for Braddon, he lobbied to ensure the royal commission into institutional responses to child sexual abuse held hearings in Tasmania.

He gave evidence at the royal commission and has also provided evidence to police.

“I became very quickly very wary of the priests,” O’Halloran told Guardian Australia.

Students were regularly called up to the priests’ rooms in the evening to discuss homework or for disciplinary reasons, and were also encouraged to visit them in their rooms to seek help with schoolwork.

O’Halloran said he was warned by older boys not to go to any of the priests’ rooms, but that a student could not refuse a request to attend.

“It was unavoidable that at some stage you were going to get called up to a priest’s room,” he said. “It was unthinkable that you would refuse to go.”

The church’s response

In a statement, the Marist Fathers, who operated the Marist College until 1974 when it was taken over by the Catholic archdiocese of Hobart, said they wished to express “deep regret and sorrow to the victims involved and to their families”.

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“In particular the Marist Fathers apologise without reservation for any hurt or harm suffered by former students who were in their care,” Marist Fathers vicar-provincial, Father Peter McMurrich, said. “We recognise that conduct of this type perpetrated by a person in a position of trust is by definition abhorrent, unacceptable, deeply damaging, and can never be excused or tolerated.”

In a separate statement, Marist Regional College principal Adrian Drane said the case was “a reminder of the mislaid trust placed in some individuals, and is a dark part of Marist Regional College’s history”.

“The entire college community offers its prayers of support to survivors of clergy sexual abuse and their families who have been, and continue to be, deeply affected by the wrongs of the past. One can only imagine the hurt, betrayal and absolute devastation of the survivors of abuse and their families.”

Drane said the school now had “systems, checks and balances … to ensure that every possible step is taken to protect our young people” and that both the school and the Catholic church in Tasmania had a “zero tolerance” for abuse.

Both statements encouraged victims of sexual abuse from members of the church to contact police.

The Catholic archdiocese of Hobart signed up to the royal commission redress scheme on 5 December.