A former prison guard has been jailed for life with a minimum non-parole period of 17 years for murdering his childhood friend Michael McGrath while continuing to deny his involvement. 

David Benbow, 54, denied killing McGrath in the Christchurch suburb of Halswell in 2017. 

In October, after an earlier hung jury, Benbow was found guilty in the High Court at Christchurch. 

The Crown alleged Benbow murdered the 49-year-old after finding out he was in a relationship with his partner of 17 years, Joanna Green. 

David Benbow was sentenced in the High Court for murdering Michael McGrath. Photo / Alden Williams 

McGrath was supposed to visit Benbow about 9am on May 22, 2017, to help him move some railway sleepers. Benbow said he never showed up, however, the Crown said the sleepers were a “ruse” and that once he arrived Benbow killed him with his .22 rifle and later disposed of his body. McGrath’s body and the firearm have never been found. 

Meanwhile, the defence said McGrath never showed up and that Benbow was in no better position than anyone to say what happened to him. 

Today, Benbow was sentenced in the High Court at Christchurch by Justice Jonathan Eaton. 

‘I despise you’ 

Sentencing began with victim impact statements being read to the court. Benbow sat in the dock and did not look at the people as they read their statements. 

McGrath’s brother, Simon McGrath, began by thanking the police for their “support, determination and commitment”, which allowed them their day in court as well as the crown prosecutors. 

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Christchurch builder Michael Craig McGrath, 49, was last seen at his home in Halswell, Christchurch, in May 2017. 

“When I think about the last six years or so, I am still left astonished and completely bewildered as to the events that began to unfold on 22 May 2017. Prior to this time, the word murder was only something that happened to other people, and whom I had no particular affiliation with.” 

Michael was one day short of a year older than Simon McGrath. Simon McGrath said he often thinks about the times they grew up together as children, the games of cricket they played in the yard, swimming at the local pool, and then later the touch rugby teams they were in. 

“I remember his laughter and the social beers we would often have together, and with our friends; the things we did in the great outdoors – tramping and cycling; the plans he would hatch and turn into reality.” 

McGrath was the “ultimate perfectionist”, hard-working, dependable and reliable. 

Michael McGrath's brother, Simon McGrath. Photo / George Heard 

He told the court about the evening of May 23, 2017, when he arrived at his mother’s home for the weekly Tuesday dinner. 

“All seemed well, apart from Michael’s car not being up the drive... However, shortly afterwards, a call to my mother from Joanna Green, would change the course of our lives forever. 

“I recall the concern on Joanna Green’s face when she later arrived at Mum’s and the subsequent conversations that I had in her car on the way around to my brother’s house. When we arrived at his home, the situation at hand became very apparent.” 

Simon entered his brother’s home through the toilet window and searched for any sign of life. 

“My anxiety levels quickly escalated once I witnessed that both his bicycles and car were still at home, and he was nowhere to be seen. I forever remember the eerie feeling I had when I walked past his car in the driveway – I thought ‘something is not right here, this feels very bad’.” 

Justice Jonathan Eaton. Photo / Iain McGregor 

Later that night he thought about Benbow telling himself, “surely, he wouldn’t have, maybe he has”. 

The next day he put together an information poster with a picture of Michael, titled “missing”, and with the help of a co-worker, dropped them in letter boxes and some businesses within the Halswell area. 

“I had an inclination that this was the end game and there was very little else I could do. Cycling to and from work each day I felt nothing but an intense sadness – the light that had shone, had simply gone out, while my emotions at work sometimes reached a tipping point and I would often have to go home. 

“The upheaval from that horrific night and thereafter was beyond my comprehension – On the first night, my mind switched to overdrive and I didn’t sleep a wink, nor did I sleep very well for a long period. A vast arrangement of thoughts would totally consume my mind. Then within some periods of sleep dreams began to emerge. There was a time that I dreamed that I had found my brother’s body, and in other dreams he would reappear home, as though he had just been away.” 

He also spoke of the “harrowing endless searching,” he did for his brother much in “previously unknown territory”. 

“I would arrive at my destination, sometimes with friends, other times alone, then the enormity of what I was undertaking struck me – I would say ‘I can’t believe I am actually doing this, I am searching for the body of my brother; there is no coming back from this’. 

Crown prosecutors Claire Boshier and Barnaby Hawes. Photo / Iain McGregor 

“Each and every exhaustive search was tortuous and soul-destroying – I didn’t want to be there, and I felt that there were much better places I would rather be, but I knew I had to give it my best shot, not only for the hope of finding Michael, but to relieve my mind. I would eventually drive home solemn and tired. When reconciling with my mind, I would reaffirm that I had to continue searching; otherwise I would always be left wondering.” 

He then addressed Benbow. 

“To the perpetrator of this horrendous act; the scheming, planning, and premeditation is beyond belief. 

“Clearly you have little remorse, and your actions to date prove this beyond any reasonable doubt. I watched in court, only to see you display your arrogance – smiling to a couple of the Corrections officers sitting beside you; and to your solicitor’s when you seemingly felt things were going your way; passing your handwritten notes; the thumbs up to your mother.” 

He said Benbow sat in court “stone-faced” as the trial progressed. 

“Are you satisfied enough but to carry on with this charade of fabrication and deception or do you wish for more?” 

Simon McGrath asked the court to consider the “magnitude and impact of this horrific crime”. 

“The convicted has displayed disturbing levels of manipulation and premeditation to bring about the execution of my brother. Then quietly and meticulously has set about the cover-up – it cannot be understated.” 

Simon McGrath reads his victim impact statement. Photo / Alden Williams

Joanna Green told the court about leaving the “toxic relationship” with Benbow. 

Then on May 23, 2017, having her “worst fear confirmed”. 

“I feared you, for my life and our daughter’s lives and our families’ lives.” 

“I showered in the dark, walked around my home in the dark. Installed cameras and personal alarm system.” 

Only once Benbow was in prison did she feel some form of safety. 

She was “emotionally and physically affected, stunted and stagnant.” 

One of their daughters blamed herself for telling him she had seen Mum and Mike kissing. 

She said McGrath “adored” their children. 

“I had always adored and respected Michael. Finding out he felt the same, going from friends to next level relationship was magic. You took Michael Craig McGrath from me. Our relationship was refreshing, honest, passionate.” 

Michael McGrath's mother, Adrienne McGrath reads her impact statement. Photo / Alden Williams

She would now allow herself to grieve for McGrath. 

“We weren’t perfect but we were perfect together.” 

She said the murder was “heinous”. 

“You’ve caused so much sadness, pain, and disbelief,” she said. “I despise you, but you will always be [our daughters’] father.” 

‘Cold-blooded’ murder 

McGrath’s father, Kevin McGrath, said he wanted to give his “sincerest gratitude” to police and all those involved in “bringing about justice”. 

The loss of his son and the way in which he died was something he had not come to terms with. 

“I don’t sleep well, constantly waking up thinking about it. They say time is a great healer, but I do not have a lot left.” 

He then addressed Benbow saying the murder was “cold-blooded, premeditated and carried out in a cowardly manner.” 

“You’ve shown no remorse and always denied what you’ve done.” 

McGrath’s mother, Adrienne McGrath, said she never imagined her life would be turned upside down the way it had. 

She experienced the pain of losing him every day. 

“I find it hard to believe that Michael will never come home again.” 

“I worry about him being out there on his own… think about how cold and lonely he must be.” 

McGrath was still not declared dead, with his mother having to maintain the property. 

She asked Benbow, “Did this mean nothing to you?” 

“You had choices, you didn’t have to take that path.” 

‘Calculated’ murder 

Crown prosecutor Barnaby Hawes said the victim impact statements showed the “devastating effects” of what happened. 

A key issue for sentencing was whether this case falls into category of murders especially bad that it required a minimum period of imprisonment of at least 17 years without parole. The Crown asked for a minimum period of 19 years in prison. 

“The murder of Mr McGrath involved calculated and lengthy planning in the way in which he was executed.” 

Crown said there was a significant aggravating factor that Benbow must know where McGrath is and what happened to him. 

“Mr Benbow could still say even now what occurred.” 

Benbow’s defence lawyer, Kirsten Gray, told the court it was acknowledged that McGrath was a “much-loved brother, son, and friend”. 

“But on Mr Benbow’s behalf, he appears before the court to be sentenced in accordance with the jury’s verdict. 

“He maintains he did not kill Mr McGrath. But in accordance with the jury’s verdict, he accepts he will be sentenced to life imprisonment.” 

The issue, Gray said, was that the minimum term of imprisonment should be. 

She said the court must consider Benbow’s personal circumstances. He is 55 years old, with no prior criminal convictions. 

“He was an engaged and loving father…” she said. 

Benbow was remanded in custody for more than two years, with considerable delay in trial from his arrest. None of those delays were his fault, she said. 

Gray said that the minimum term of imprisonment should be around 14 years, acknowledging an uplift due to the body not being located 

‘Meticulous, but also fortuitous’ 

Justice Eaton acknowledged McGrath’s family and friends in court as well as Benbow’s family. 

“I’m very conscious you maintain your innocence,” he said to Benbow. 

“But I must sentence you in accordance with the jury’s verdict.” 

Eaton then went through the background of the case, including Benbow and McGrath’s friendship. 

He did not consider it a confidence he told his counsellor he wanted to “annihilate Mr McGrath”. 

Justice Eaton said Benbow was ruminating over the relationship between Green and McGrath. 

“That state of mind provides the essential backdrop of what took place.” 

Justice Eaton said Benbow’s request for McGrath to come over to help with the railway sleepers was a “ruse”. 

The most likely mechanism for the murder was Benbow shooting McGrath in the head with a .22 rifle. The absence of forensic evidence indicated he carried it out “carefully”. 

He was able to present to his counsellor and others after the murder as “calm and confident”. 

Justice Eaton said the murder was “both meticulous but also fortuitous.” 

He said Benbow was not willing to stand by and watch McGrath’s relationship with Green and his children. 

Justice Eaton acknowledged he was and remained a “devoted” father. 

He was conscious Benbow continued to deny any involvement and therefore expressed no remorse. 

The murder was an “execution style killing”, he said with the level of planning and premeditation standing out. 

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.