On each visit he would stay for up to an hour - sitting not with his relative who was in a hospital wing nearby - but in the lounge on the rest home side, where he would chat to other residents he referred to as his "friends".
He always arrived alone.
"I have never seen Grant bring anyone else with him on his visits," the manager said. But before the assault, no one thought anything of it. "There was nothing about Grant that would raise my suspicion or concern about him."
In hindsight, however, staff said they couldn't really explain what he had been doing.
"I don't know of any reason why he would be in the rest home side," one carer said. "I don't think he had reason to be there."
Building a case
Hannis, 55, was convicted of indecent assault against the elderly dementia sufferer in January this year.
The attack occurred the previous May. Hannis was caught by a caregiver in the woman's room. She said he followed her there and forced himself on her.
Documents on the police file show how detectives built their case. They first interviewed witnesses who had seen Hannis talking to the victim in the lounge by the fire during the late afternoon.
He moved from a chair next to her, to sitting beside her on the sofa, the witnesses said. He then followed her to her bedroom - his movements tracked by CCTV.
The pair were interrupted when the caregiver needed to charge her phone. The victim had the same charger, the caregiver said, and let her use it in her room. The CCTV shows the caregiver heading to the room, phone in hand, and then leaving and returning shortly afterwards with a nurse.
"I was shocked because he shouldn't be in her room," the caregiver said. "I recognised the man as Grant."
Initially, the victim denied anything was wrong, but both the caregiver and the nurse were suspicious - particularly after they noticed she had changed clothes. Later, blood was found in her underwear. The nurse told the clinical manager about the incident, who then spoke to the victim several times to try and find out more.
It took a full day for the woman to reveal what Hannis had done to her. She broke down in tears and swore the manager to secrecy, calling it "disgusting". The manager explained they had to call the police, and the woman agreed to a medical examination and interview.
During the interview the woman told police how she tried to push Hannis off but he was "too forceful" and "wouldn't stop". She said she had never been sexually assaulted before.
'I just chat to the residents sometimes to be friendly'
The documents detail how as well as conducting interviews and viewing CCTV footage, police collected evidence from the victim's room. Hannis had not been approached at this point.
Because he was a regular visitor, a safety plan had been agreed between police and staff. Hannis was to be watched by a staff member as soon as he entered the premises, it said. If he was alone with a resident or tried to go into their room, the staff were instructed to call police.
On Wednesday June 1, three days after the attack, plain-clothes detectives visited the rest home with forensic equipment. Unable to find a key to the victim's room, they forced it open and began a scene examination, collecting clothes and a flannel they thought might hold DNA.
Around 2pm, a staff member told an officer Hannis had arrived at the home. The officer described what happened next in his notebook.
"I saw the male suspect on the other side of the long corridor near the dining room. He was by himself and not carrying anything and walking towards my direction," he said.
The victim had moved rooms while the search was ongoing, and was further up the corridor, with her daughter. As Hannis walked past, he looked in, the officer said, but didn't stay.
"The male suspect continued walking towards me. As he was walking past [victim's room] he had a look in the room. The door was open, there were broken door lock parts and damaged door pieces on the floor. It was very obvious [what was happening]."
Hannis carried on walking, but before he reached the corridor's end, he turned and went back past the policeman. At that point, the officer chased him.
"Excuse me, sir. What's your name," he said. He showed Hannis his badge, and asked why he was there. Hannis replied he was visiting the victim. When the officer pointed out he'd walked right past her, Hannis asked if there was something wrong.
"Did something happen to [the victim]?" Hannis said.
The officer replied "yes", then informed Hannis he was under arrest. While waiting for another officer to collect him, Hannis asked twice more about the victim. In one question he said: "Was [the victim] raped by someone?"
Later, at the station, Hannis was asked why he had been on the rest home side when his relative was in the hospital wing.
"I just chat to the residents sometimes to be friendly," he said.
In the car back to his house, Hannis told an officer he'd known the victim for about six months. He said he'd seen her photos. He said he played in a jazz band and she liked his music. Hannis' band had played at the past three Christmas parties, the manager said.
When the victim was asked about Hannis, she said she didn't know his name. She only recognised him as the man who did the sing-a-longs, she said.
A fall from grace
During sentencing, the woman's daughter described how since the attack, her mother hasn't been the same, the "bright spark" in her eyes now dull. "Our mum has slowly drifted away."
When Hannis was first charged - some time after his initial arrest - he denied sexual contact with the victim. He then suggested she'd "done it to herself". Later, he said the interaction was consensual, and that the pair were "private lovers".
He refused to plead to a charge of unlawful sexual connection, only admitting guilt when it was downgraded to indecent assault as part of a plea bargain - agreed to by police in part to save the elderly victim the trauma of a trial.
Hannis tried hard to keep his name a secret, arguing he should get suppression because he was mentally unwell. His request was denied.
During the sentencing process, Judge Stephen Harrop earlier described what Hannis did as "unbelievable offending".
When calculating the sentence, Judge Harrop took into account Hannis' previous good character, his contribution to the community, and his remorse, as well as the decision to lift name suppression.
He said the incident was a fall from grace for Hannis, a former head of department and a celebrated academic.
Harrop sentenced Hannis to eight months' home detention, 100 hours' community work and ordered him to pay $3000 in emotional harm reparation.
Hannis continued teaching for six months after his arrest. Massey University, his employer, said it was never told about his arrest or the charges he was facing.
In March, the Herald revealed Hannis was investigated over a second sexual assault complaint, also involving an elderly woman.
Police sought to charge him with a second crime - also involving an elderly woman at a rest home - but did not have enough evidence to get it to prosecution.
For a case to go to court in New Zealand there needs to be enough credible evidence for there to a "reasonable prospect" a jury will convict.
Around 80 per cent of aggravated sexual assault cases where police believe the victim are not prosecuted, mainly because they do not meet that threshold.
Hannis denied the second charge.
The Herald has since sought access to the second investigation file, but so far it has not been released due to the victim's wish to privacy. The case is now with the Ombudsman.
Hannis' sentence will end in September this year.
His victim, who was able to walk by herself prior to the attack, is now in a wheelchair.