A Dunedin King's High School teacher only admitted having a sexual relationship with a pupil after images circulated on social media showing her in bed with a different former pupil.
Two documents provided anonymously to the Otago Daily Times -- which included a letter sent to the teacher by rector Dan Reddiex -- also showed the school investigated the first relationship in the middle of last year, but the teacher "vehemently denied" the accusations and no proof was found.
This comes as a current pupil, who wishes to remain anonymous, said almost everyone at the school had seen two intimate images of the teacher.
The second image circulating appeared to be a selfie sent by the teacher on Snapchat with the caption: "Well I have keys...and after hours Acces [sic]."
The teacher was immediately suspended after telling Mr Reddiex about the first relationship last Wednesday and subsequently resigned.
Mr Reddiex said he was not being misleading when he told the ODT on Sunday the relationship was "isolated" to one case.
This was because he was confident the second relationship happened after the pupil left school at the end of last year and did not begin while he was a pupil.
"From the conversations I have had I am pretty comfortable that didn't take place.
"As comfortable as I can be."
His previous response that he only found out about the relationship when the teacher came to him last week was also accurate, as nothing was proven when the investigation was carried out mid-way through last year.
"There was no evidence, there was no grounds upon which to take any further action or suspect wrongdoing and you can't consider people guilty purely [based on] speculation and allegation.
"I wasn't being misleading at all because I didn't know about the nature of that relationship literally until she walked in my door on that Wednesday."
He did not think anything more could have been done during last year's investigation.
"We certainly followed the correct process and for whatever reason people chose to vehemently deny [the accusations]."
Asked if he was concerned most of the pupils had seen the images of the teacher, he said he would speak to the pupils about the matter today.
The letter from Mr Reddiex said the teacher was accompanied by her parents when she revealed to him she had a relationship with a pupil last year.
It goes on to say: "The catalyst for this disclosure was a subsequent sexual relationship that you have have had in 2016 with a former Year 13 student that has resulted in posts on social media, particularly Facebook."
A second document contained notes Mr Reddiex made during an investigation into the first relationship after accusations were made mid-way through last year.
In the notes he said that when confronted with the accusations the teacher "vehemently denied this accusation and was visibly upset at the intimation".
When the pupil was asked if there had been a relationship, his immediate response was "I wish" before carrying on to say he had not had a relationship with the teacher.
A current pupil, who wishes to remain anonymous, said almost everyone at the school had seen the images and were talking about them last week -- their first week back after the summer holidays.
"Nobody is talking about anything else."
Asked what pupils were saying, he said they were sad the teacher had left because she "was probably ... the nicest teacher."
Asked if the teacher acted inappropriately with pupils, he said: "She was very comfortable around them, like putting her feet up on the students."