How Christchurch killer David Benbow’s texts to a journalist ended up in a High Court trial

On Tuesday, David Charles Benbow will be sentenced for murdering his childhood friend Michael McGrath nearly seven years after he disappeared. Herald senior crime reporter Sam Sherwood reports on how a series of text messages from a man who called himself “Nigel” led to him being called as a Crown witness in a murder trial.

“Hello, Sam. You inquired about a witch-hunt of a good friend of mine,” the conversation began shortly after I arrived home from work.

Looking at my phone, I knew instantly that the message from the unknown number related to an approach I’d made two days earlier to David Benbow.

It was nearly 300 days since his childhood friend Michael McGrath went missing and Benbow had just put his family home on Candy’s Rd up for sale a second time.

He’d tried selling it several months earlier with another real estate agent, but following media coverage of the listing, they decided to pull out as it was “too much hassle”.

McGrath had done some work on the property, helping Benbow work on a deck and also making a playhouse for his children.

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

McGrath’s disappearance on May 22, 2017 made national headlines, with several police press conferences being held as detectives appealed for sightings of the 49-year-old.

However, to date, Benbow, whom police said was a “person of interest”, was yet to make any public comment aside from telling a reporter from the Press he was the victim of a witch-hunt.

I had spent many hours looking for another way to contact Benbow. I couldn’t find a Facebook account, and he was not in the phone book. I had tried calling his mum but she did not want to comment.

It was not until March 2018, when his house was listed for sale a second time, that I got what I was after. I went online and the real estate agency had uploaded several documents related to the house. As I scanned the documents, I spotted one which included Benbow’s cellphone number. Finally, I had an avenue through which I could communicate with him.

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I wasn’t under any impression he would agree to an hour-long interview but felt it was important, given I was intending on writing a story, that I give him a chance to comment.

I called on March 14, the phone rang and Benbow answered. He wasn’t interested in talking.

I then sent him a text saying I wanted to give him the opportunity to talk about how the last 300 days had been for him. I said I had some questions for him, including how he believed he was the victim of a “witch-hunt”.

I got no response and thought that was the end of it.

David Benbow will be sentenced in the High Court at Christchurch on Tuesday. Photo / Iain McGregor

Then, two days later on March 16, 2018, I received the first message from an unknown number.

Another text followed saying Joanna Green, Benbow’s ex-partner, had “triggered the investigation”. They claimed Green had a “chronic drinking problem”.

“Confirmed is in new relationship with Michael,” they said before alleging Green “can be violent on occasions”.

I asked who I was speaking to, and they said their name was Nigel. I was immediately suspicious about who was really behind the texts - in the back of my mind, I wondered, ‘What’s this man, whom I believe to be Benbow, going to tell me? Will he slip up?’

“The police have never searched her rental house… or her car,” the messages continued.

“She is a person of interest, but you don’t put her photo in the press and occupation.”

I asked Nigel whether Benbow would be happy to speak to me, hoping I would finally get an interview with him. Nigel said he would ask him the next day.

At the first trial, David Benbow admitted being the person behind the text messages. Photo / George Heard

I told Nigel that at the time I was not in possession of a photo of Green, which was why we had not published any.

“Because your 1 dimensional eg witchhunt, getting the idea now [sic],” Nigel said. The word witch-hunt, which by now Nigel had used twice, piqued my suspicions further, given it was the term I had used in my text to Benbow.

He then told me to go to Green’s workplace the following Monday morning to get a photo of her, supplying her number plate to make it easier to find her.

I then asked Nigel how his good friend was coping, hoping I might be able to use these comments later down the track if I were ever able to confirm Benbow was behind the phone number.

“Ask yourself the question. David has had his life turned upside-down, all the press coverage, 300 days of no evidence. I don’t think David is that clever. But I bet you publish another article in the morning.”

Nigel then tells me two young girls were sitting in the gutter opposite McGrath’s house in the early hours of the morning over the period in question, which was reported by a neighbour but had not been mentioned.

“A commotion and loud voices reported about 2.45am over that period by three neighbours. One neighbour witnessed a vehicle driving off. It wasn’t David’s vehicle and he wasn’t present. But the police still promoted his vehicle on [Police Ten 7].”

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

Keen to see what more “Nigel” would tell me, I asked why he thought police were treating Benbow the way they were and whether he thought McGrath was still alive.

“It’s not just the police, look at the way you are treating David. As outlined, they have not looked outside the box and explored all other options. One would presume vital evidence has now been lost if anything untoward has happened to McGrath.”

I replied it must be hard for Benbow not knowing what happened, considering they were “good friends”.

“They were good friends and he hasn’t been given a chance to grieve over a missing friend. Also, information circulating [suggests] Michael McGrath [was] not a complete angel as displayed,” he replied.

I asked what sort of information he was referring to, and Nigel replied: “Maybe [we’ll] talk next week. You have enough to go on for now. See what you deliver. Cheers, Nigel.”

I saved the number in my phone as “Benbow’s friend” and sent three more texts to Nigel with questions, but I never heard back.

I also texted Benbow on March 21, saying I had been talking to “Nigel”, and wanted to see if he wanted to talk. There was no response.

After about a week, I informed the officer in charge of the case at the time about the messages, believing I was likely talking to Benbow and that he was using a phone number that may not be known to police, thinking it might be of use.

Nearly five years on, I sat in the High Court at Christchurch reading the messages in open court. Asked by the Crown why I was confident I was speaking to Benbow, I said the term “witch-hunt” and the amount of information the person had about Green’s car and when she left work had piqued my suspicions.

After I left the courtroom, a police officer gave evidence about how police were able to identify the Sim card for the number belonging to “Nigel” that had been used in Benbow’s cellphone.

It also emerged Benbow actually admitted to sending me the text messages. However, the exact reason why remains unknown.

The trial ended with the jury unable to reach a verdict and a retrial was ordered.

About a week before the retrial, I was advised by police that the defence had opposed the admissibility of my evidence and that the judge had ruled in their favour, meaning I would not be called for the second trial.

Benbow’s defence argued the jury could find him using the alias Nigel and a new Sim card was “unusual conduct”, and gave risk the jury would draw an “adverse inference” as to his character.

They believed such an inference would be wrong and unfair as Benbow was “simply responding to persistent media requests that he comment on the police investigation”.

Alternatively, the defence suggested the text messages could be admitted as evidence, but that the Crown should not be allowed to mention that Benbow used a false name and a new Sim card.

In reply, the Crown said the evidence was another strand of its circumstantial case.

They said that in referring to “grieving”, a jury would be entitled to infer Benbow knew McGrath was dead rather than missing.

They also argued that the “disparaging comments” about Green were “probative of guilt” and reflected an attempt by Benbow to distance himself from the police investigation.

Justice Jonathan Eaton did not accept the Crown’s arguments and said the fact Benbow used an alias and a different phone number was of “low probative value”.

“Whilst I do not consider the evidence would have a significant prejudicial effect on the proceedings, it is likely to lead the jury to consider Mr Benbow’s behaviour to have been odd.

“There is a risk the jury would equate odd behaviour with guilt. That would give rise to unfair prejudice.”

In the end, it did not matter. Benbow was convicted of McGrath’s murder.

On Tuesday, he will be sentenced in the High Court at Christchurch.

McGrath’s brother, Simon McGrath, told the Herald he believed the messages were “another level of deception”.

“Why would a so-called innocent person do that? It’s quite weird behaviour… to go to that level of deception, assuming a friend was supporting him. Most people, if they’re innocent, will just text from their own phone or give you a call.

“It’s just another line of deception.”

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.