Former prison guard David Benbow was today sentenced to life imprisonment with a minimum non-parole period of 17 years for the murder of childhood friend Michael McGrath. Herald senior crime reporter Sam Sherwood sat down with the officer in charge of Operation Renovation.
Detective Inspector Kylie Schaare was only days removed from being inside a courtroom for a murder trial - a brutal criminal underworld case of mistaken identity - when she was walking down the hallway at Christchurch police’s temporary station and told she was needed to assist with another investigation.
A builder by the name of Michael McGrath had been missing for six days after failing to turn up for the weekly family dinner at his mother’s home on May 23, 2017.
Schaare, who at that stage had worked in the police for about 18 years, was assigned second in charge of the investigation, dubbed Operation Renovation due to McGrath renovating his home at the time of his disappearance.
It would become abundantly clear to Schaare and the rest of the team the case was not your standard missing person inquiry as it transitioned into a homicide investigation with no body, and no murder weapon.
The investigation was one of the biggest area inquiries by police in the district, involving 8000 man-hours dredging 2500 tonnes of rubbish at the Kate Valley Landfill in the Hurunui foothills, and divers searching lakes and rivers for clues.
“It was back to detective 101... it really came down to that old-school attention to detail, every little thing,” Schaare tells the Herald.
It would take two years and four months before police would arrest McGrath’s childhood friend, David Benbow, on the former prison guard’s 51st birthday and charge him with murder.
Another four years would go by before a second jury, the first was unable to reach a verdict, would find Benbow guilty of murder.
On Tuesday, Benbow was sentenced to life imprisonment with a minimum non-parole period of 17 years.
With his sentence handed down, the Herald takes a look inside Operation Renovation.
Every Tuesday for more than 20 years, Michael and Simon McGrath would go to their mum’s house for dinner. Michael had only missed it once or twice, so when he failed to turn up on May 23, 2017, without explanation, alarm bells rang.
“We’re always keeping an open mind,” Schaare recalls.
“It was coded as a missing person... that’s what we were focused on.”
In the early stages of a homicide investigation, there would be two briefings a day, the first early in the morning with everyone gathering together and having some input.
“It’s just a matter of assessing okay, so what do we now know, what information has come in, what needs to be done. What are the priorities, what are the taskings.”
It was clear to the team early on that it was “very out of character” for McGrath to “just disappear”.
There was also no sign of any disturbance at his home, all his modes of transport were there, including his bike and car as was his Eftpos card.
In any homicide investigation, someone’s habits and movements tell police a lot and can help guide them in various directions.
“You’re trying to get a sense of who that person is. What’s their normal pattern of life? That pattern of life will tell us who people are in contact with, whether that’s family, friends, associates or workmates.”
With McGrath, it became clear he was “very much a creature of habit,” who didn’t have a wide social network.
“He was actually quite insular in his pattern of life, and didn’t move far out of Halswell. Unlike potentially other people who may be extroverts out socialising and have a much wider group of people they come into contact with,” Schaare says.
“Looking at the overall picture and what we then knew about Michael, something really bad had happened to this man for him not to be in contact with his family.
“He wasn’t just going to walk away from everything he knew and just disappear.”
A key piece of information that came to the attention of the investigation team early on was a new relationship McGrath was in with a woman, Joanna Green.
Green was the ex-partner of McGrath’s childhood friend, David Benbow.
Benbow, then a prison guard, had weeks earlier been told by one of his daughters they’d seen their mum and McGrath kissing. He’d told a mate he was pissed off, and had called in sick to work.
He’d also visited his counsellor. The break-up with Green had left him lost, confused, and lonely.
His health was going downhill, he wasn’t sleeping or eating. He felt shafted, a word she underlined in her notes.
He then told the counsellor that one of his mates was starting to see Green. He told her he wanted to “annihilate” him.
The night he was reported missing, Green immediately called Benbow, asking him: “What have you done with him?”
After going to McGrath’s house with Simon and not finding him home, she phoned police to report him missing.
“I am thinking that he has hurt Mike,” she said.
On May 26, police brought Benbow in for questioning.
He told Detective Sergeant Aaron Paulsen he was “concerned” about McGrath and he missed him.
He appeared relaxed, even playing down his feelings over Green’s new relationship with Michael, saying it was none of his business as they had split up.
“You sort of think about it, but you move on,” he told Detective Sergeant Aaron Paulsen.
He said he’d been to McGrath’s home on May 21 to see if he could give him a hand to move some sleepers out of the way.
McGrath was going to pop over about 9am the following morning to help.
“He seemed in good spirits,” Benbow said.
However, the next morning McGrath didn’t show up, he claimed. He presumed it was due to the “hard frost”.
He eventually left to go to a counselling appointment before seeing someone about rust repairs for his Camry and then checking on his mother’s house in Viceroy Place in Halswell. He returned home to work around the house, he said.
“I wasn’t that concerned, I just thought oh, you know, he’ll show up when he shows up...”
He said he couldn’t remember what he did the night before.
About a week later, Benbow was interviewed again. Police couldn’t find his Marlin 795 .22 semi-automatic rifle. It wasn’t where Benbow said it should be and he had no explanation for that.
Detective Sergeant Phillip Sparks put it straight to him that he was behind McGrath’s disappearance.
“I haven’t had anything to do with the disappearance of Michael... I wouldn’t do anything,” he said.
Asked to give one good reason why he should be believed, Benbow replied: “Cos I haven’t done anything... I don’t have a motive. I’m not that sort of person.”
But Sparks suggested he did have a motive, that he had told his sister-in-law Toni Green that Jo and Mike had been shagging and that “every human has got a breaking point”.
Benbow pushed back, saying he was just burnt out from the stress of house repairs and work, but was not broken.
“I can see you’re pushing me, just trying to push me into something,” he said.
“I’ve given the truth, I haven’t done anything... I know it looks bad, but how do you think I feel... makes me look like a c*** doesn’t it.”
Schaare says at the beginning of the investigation, Benbow was a person of interest, as were many others.
“We never publicly said that he was a suspect, we were very careful not to do that.
“If you look at any homicide investigation we’re looking for the people that are in contact with our person. Those people surrounding that person are people of interest to the investigation until we can exclude them.
“Having motive we’re obviously going to be looking at somebody and we work hard to exclude them from the investigation and if we can’t then obviously we will be looking at them some more.”
As the investigation progressed, eliminating persons of interest one by one, one name stuck around.
“We are literally left with one person and we are looking at everything and other possibilities. But at the end of the day... there was no other possible person of interest here.
“There is no other logical, plausible explanation for Michael’s disappearance. There’s no one left other than this person, whose got means, motive, opportunity.”
For police, one of the big obstacles was that they were working against time.
“For something like this, it’s quite clear now that it was pre-planned, pre-meditated.”
It wasn’t until May 31 that police seized Benbow’s Candy’s Rd home.
“That’s a massive barrier. As it turned with the benefit of looking back, the offender was two weeks ahead of you. With that comes big factors for an investigation and that’s destruction of evidence or degradation of evidence particularly with a key outside scene exposed to weather and clean up.”
For Schaare and the rest of the Operation Renovation team, solving the case was going to require a different approach than most modern-day investigations.
“Michael was almost old school and that reflected in what we had to do in this investigation and that was almost go back to old school policing, before internet, computers and phones, which can be used to establish evidence these days, it wasn’t such a prominent a factor in this investigation. It really came back to that old school attention to detail, every little thing.”
Police did, however, have CCTV footage showing Benbow on May 23, the day after McGrath was believed to have been killed, arriving at the Parkhouse Rd Eco-drop transfer station. Footage showed him throwing some items including a long, skinny, rigid, item about 1m long and a plastic bag.
The footage led police to the Kate Valley Landfill, where staff spent more than two months sifting through hundreds of tonnes of waste.
They were trying to find anything that could help, but mainly they were on the lookout for clothing, McGrath’s keys and the gun.
“We had a massive commitment across the district,” Schaare says.
“There’s probably not a staff member in this district that wasn’t involved at some point.”
After about 8000 man-hours and 2500 tonnes of rubbish, police walked away empty-handed.
However, it wasn’t the only area police were looking. On July 17, 2017, police covertly placed a tracking device on Benbow’s Camry. On the advice of a geoforensic search specialist, police released a tactical media release detailing that an international expert had been working with police.
The release detailed that police had identified geographical areas of interest in the greater Christchurch area and that specialist search teams would be brought in to search those areas.
A day after the media release, Benbow received a call from a friend asking if he’d seen the news about the release.
The friend then told him that police had brought in an international specialist and would be searching other areas.
“Well, they’re leaving no stone unturned, so good,” Benbow said.
Days later, Benbow made two trips of interest to police. The first was to a rural address in Motukara where he stopped for almost three minutes.
The next day he drove to the same area, but stopped at the intersection of Ridge Rd, Hudsons Rd, Geddes Rd and Davidsons Rd for 38 seconds, and then another 35-second stop outside a property on Ellesmere Rd on his return home.
The two trips were the only times he went to that area during the nearly six months his car was being tracked.
“Obviously seeing movement within close proximity to that was clearly of interest to us. It was out-of-character movement that we hadn’t seen before and couldn’t account for. All the other movements had a connection - a friend’s address, an appointment or shopping...”
The trips led to another phase in the investigation - searching the Halswell River, with the national dive squad called in.
It was another “needle in a haystack”, Schaare says, with widespread flooding in July making things more problematic.
As the months rolled on, the workload for Schaare and the rest of the team didn’t get easier with other investigations to work on as well.
Then on March 15, 2019, a terrorist attacked two mosques in Christchurch, killing 51 people.
Schaare was called into the investigation, dubbed Operation Deans, as the officer in charge of suspects.
After completing her role in the inquiry, Schaare and the core team in Operation Renovation gathered once more in the homicide base at the Christchurch Central Police Station to do a full review of the investigation, with a push to complete the CCTV phase.
“We had a large amount of CCTV, hundreds of hours and someone has to actually watch that in normal time, and you can’t do that at the front end all the time. You had to prioritise what you’re going to do and when you’re going to do it,” Schaare said.
“One of the big factors was Kate Valley and the fight against time and degradation. There was a priority on that, we’ve got all this information such as CCTV, it’s not going anywhere it’s not going to get destroyed.”
It was during the review, which took about three months, that Schaare says the team “got some gold”.
The gold was CCTV footage from two cameras on a property Benbow used to own on Wales St. The footage showed a car police believed was McGrath’s blue Subaru station wagon heading Benbow’s way, on the Monday morning, about 8.54am.
One minute later, the New World supermarket’s CCTV camera captured what police believed was the same Subaru turning town Oakridge St, heading in the direction of Candy’s Rd.
“It was confirmation we were on the right track. It’s drilled into detectives that we always keep an open mind and I know it’s been suggested otherwise but even with that we’re thinking okay, that probably means that, but what else could it mean, what else could it be?”
Schaare says by the time the team got to the end of the review, she felt comfortable they had enough to arrest Benbow.
“It’s looking at the totality of all the information that you have... having it all laid out, thread by thread as it all builds up.”
The day before the arrest, she informed the McGraths of what was about to happen.
“The fact that we didn’t arrest until September 2019 would’ve been really hard on the family but I wanted to be entirely comfortable that we’d done everything that we could, we had conducted a thorough and objective investigation and we were on really solid ground and had sufficient evidence to charge someone.
“It is never a decision we make lightly and it’s a decision based on facts, evidence, and evidential sufficiency.”
It wasn’t until February 2023 that the first trial got under way in the High Court at Christchurch.
However, after hearing from more than 100 witnesses over seven weeks and deliberating for 23 hours, the jury was unable to reach a verdict.
Schaare says her first reaction was thinking about the impact it would have on the McGrath family.
“They’d already had a massive journey and I knew that was just going to add to the pressure for them to go through a trial again... it was hugely physically and mentally straining for families and people giving evidence.”
About four months later, the second trial began before a jury of 12.
Crown prosecutor Barnaby Hawes closed the Crown case by acknowledging it was a circumstantial case, with no body to examine, no murder weapon, no DNA and no confessions.
However, he said the case against Benbow was “compelling and it’s decisive”.
“Mr Benbow is a careful and deliberate man but everyone makes mistakes... He’s hidden his body well and utilised an outdoor scene to his advantage, kept things very simple and spoken to nobody about it. Nevertheless, I suggest the facts speak for themselves and prove murder beyond reasonable doubt.”
He told the jury that if they found a set of individually reliable facts to not look at them individually, but in combination.
He asked the jury whether Benbow had just been unlucky to have “significant” evidence suggesting his involvement in a homicide, or was it that he was involved.
“That’s not like lightning striking twice in the same place. In the context of this case, this is lightning striking the same place over and over again.”
In her closing, Benbow’s lawyer Kirsten Gray said the Crown’s case was based on a “theory”.
“A theory that was first thought up by Joanna Green, the theory that Mr Benbow had done something to Mr McGrath. And it’s a theory that is desperately searching for evidence,” she said.
Gray referred to the Crown suggesting the case was like strands of a rope, that once they come together make a rope so strong that you can rely on it beyond reasonable doubt.
“Be very cautious about that submission. If you look at the strands of the rope in detail, you might be left scratching your head. The strength of the rope, members of the jury, is your domain, it’s for you to decide. But you need to ask yourselves at the outset, do you accept that this is a rope or, as I suggest, is it just a pile of tattered threads, a house of cards not capable of withstanding any serious probing?”
She said the jury had more evidence that police focused only on Benbow than evidence of anything else, citing the 8000 hours they spent searching a dump compared to the 800 hours looking for McGrath.
“This doesn’t amount to a rope and it certainly doesn’t get you to the high standard of beyond reasonable doubt.
“In my submission, the Crown case is a house of cards built on shakey foundations which if you give it any real probing will simply fall over and if you drill into what is being alleged then things don’t make sense and the improbability of their entire case is glaringly obvious.”
After 18 hours of deliberation, the jury had a verdict - guilty.
“The first emotion is just absolute relief,” Schaare recalls.
“Then it’s what does this mean for the McGrath family... my big hope was finally some form of closure. It doesn’t bring Michael back, it doesn’t change what’s happened but they’ve finally got some answers. Hearing the verdict was like I hope this will start them on the journey to reclaiming their lives a little bit.”
Moments after the verdict was given, Schaare got to speak to McGrath’s brother, the elation evident from the smile on his face.
The journey goes on for the McGrath family. Michael is still not officially declared dead, leaving his home in limbo while his mother keeps maintaining the property.
“There’s no place that they can go and remember him or grieve. They don’t have his body back. You can’t not have empathy for a family in that situation.”
She thinks back to the beginning of the investigation, meeting with the McGraths, telling them they would do their best to solve Michael’s disappearance.
“They’re going through the worst time of their lives and asking someone that doesn’t know you to place all their faith in you and your team... It’s a huge ask for them to just trust that we know what we’re doing.
“It’s an important ethos I remind investigators, that there’s no greater responsibility or privilege than investigating the death of someone’s loved one. You strive to give them the level of commitment that you would expect if it was your family member, you deliver the level of service and commitment you would expect and that’s what we do, it’s no more or no less.”
She says she’s never given up looking for Michael, and has always wanted to bring him home.
“I think nearly seven years on the reality is only one person knows where Michael is and we’ve certainly done our absolute best to try and find him.”
Despite no body, no murder weapon and no DNA evidence, Schaare says there’s no such thing as a “perfect murder”.
“Everyone does make mistakes, humans are fallible they make mistakes. I really want to acknowledge the investigators and the Crown that have worked on this. It boils down to commitment and tenacity - it’s been a big journey.
“We weren’t going to give up on this. That’s not a lack of objectivity, this is someone’s son and you don’t just walk away when things are difficult. You have to actually put in the hard yards and the staff working on this have absolutely done that and the Crown, which has got us to this point.”
Sam Sherwood is a Christchurch-based reporter who covers crime. He is a senior journalist who joined the Herald in 2022, and has worked as a journalist for 10 years.
The 19-year-old disappeared without her wallet or mobile phone.