The prisoner and the officer gave conflicting evidence.
"The employment investigation found that the Corrections officer spent time alone with a prisoner in the engineering workshop and that the Corrections officer failed to maintain appropriate boundaries with the prisoner," the summary said.
"These concerns are held for the following reasons: the prisoner is adamant he saw the Corrections officer and engaged in conversation for a significant time, 10 to 15 minutes; the Corrections officer stated in their interview that they did not see the prisoner nor speak with him.
"The statement by the Corrections officer is determined to be highly unlikely as the evidence shows the prisoner and Corrections officer entering the engineering workshop within one minute of each other."
Despite this, the prison director found the allegation of failing to maintain appropriate boundaries was not proven and "therefore the allegation of inappropriate behaviour or relationship was not upheld".
"There is no evidence that the Corrections officer and prisoner entered a non-monitored room together," the summary said of the director's decision.
"The prison director decided that the Corrections officer acted with careless or unsafe behaviour [and had] fallen short of the expectation of the department and is in breach of the ... code of conduct."
The officer received a written warning.
A Corrections spokeswoman confirmed on Friday that the officer remained with the department.
Asked why the director overruled the investigators' findings, the spokeswoman said the director considered the layout and could not corroborate what the prisoner told the investigator. He decided it had not been proven that the two were in the same place at the same time in the building.