Tasmania's education department secretary says it was "woefully inadequate" that allegations a male teacher kissed and inappropriately touched a female student were not investigated.
At a meeting with department staff in the 2000s, Rachel, a pseudonym, also claimed the teacher had given her alcohol, written her a love letter and exposed her to dirty videos and jokes.
Department secretary Tim Bullard, who has been in the role since 2018, on Thursday gave evidence at a commission of inquiry examining the handling of child sex abuse accusations in Tasmania's public service.
"My understanding is that the dirty jokes or videos ... were the subject of further investigation," he said.
"My understanding is the other allegations ... were not. They absolutely should have been.
"The department's response to this was woefully inadequate. I apologise to Rachel for the manner in which it was handled."
Rachel had years earlier made a complaint against the teacher in relation to other allegations.
She said he had tucked her into bed, described her bottom as "nice", drawn an explicit image on her ankle, piggybacked her, provided her with alcohol and contacted her when ordered not to do so.
Those claims were proven following a two-year independent investigation, the inquiry heard, but deemed "not relevant" because they were not in the course of his employment.
Mr Bullard said that determination would "absolutely" not be made today.
"At the time that this occurred there were some policies around fraternising, or friendships, with students. They were framed more as advisory than mandatory," he said.
"We now have the conduct and behaviour standards which makes it very clear that the conduct displayed ... is not acceptable."
A notice authorised by the department was later published in a newspaper, saying the teacher was found to have not breached the State Service Act and had accepted another education job.
The inquiry was shown a letter from the department to the teacher, indicating current investigations had been closed and the act had not been breached.
"However ... I am concerned that you chose to draw (an inappropriate image)," it reads.
"I believe you showed poor judgement when undertaking this action.
"I require you to show more appropriate judgement when dealing with students at any time in the future."
A letter from the education department was sent to the Teachers Registration Board (TRB) saying the investigation into the teacher had concluded.
It didn't mention Rachel's allegations made at the meeting. Mr Bullard agreed the department had, by omission, misled the regulator.
Mr Bullard said the teacher has been suspended and has been referred to police.
Rachel gave evidence on Wednesday, saying she was never told whether her disclosures at the meeting had been investigated.
The inquiry has previously heard 32 education department staff have been stood down in the past 18 months in relation to "historical allegations".