David Benbow is standing trial for the alleged murder of Michael McGrath (inset). Photos / Pool, Supplied
David Benbow is standing trial for the alleged murder of Michael McGrath (inset). Photos / Pool, Supplied
An expert defence witness who reviewed alleged murder victim Michael McGrath’s home power consumption data and concluded he was “definitely” home at a time police allege he was killed several kilometres away has today admitted it’s not possible to definitively say if he was home or not.
Electricity consumption records at McGrath’s Checketts Ave house in the Christchurch suburb of Halswell have come under scrutiny in the sixth week of the High Court murder trial of David Benbow.
The Crown alleges that Benbow, 54, lured his builder friend McGrath to his Candys Rd home at 9am on May 22, 2017, to help him move some heavy railway sleepers. It says Benbow shot him dead before attending a counselling session in the city at 10.15am and later dumping his body.
McGrath has never been found and nor has any murder weapon.
During its opening address to the jury, the Crown said it knows McGrath was alive that morning because power “spiked” at his Checketts Ave home between 8.30am and 9am as he made his breakfast and got ready for the day.
But after he allegedly left for Benbow’s about 9am, there was no significant power use “indicating that no one was home after that time”.
Genesis Energy employee Catherine Mace earlier said 1kWh of power consumption at McGrath’s house between 8.30am and 9am, suggested it could have been someone going about their normal morning business.
The electricity meter at the house was subject to automation, the court heard, with power going on and off at intervals throughout that day.
But she was recalled to the witness stand on Tuesday morning, saying that she had made some further inquiries and discovered she had made a mistake.
David Benbow has pleaded not guilty and is on trial at the Christchurch High Court for murdering Michael McGrath in 2017. Photo / George Heard
She said the time bracket was now for 9am-9.30am - and that she had apologised to police for her error.
Private energy industry consultant Ron Beatty reviewed McGrath’s power records and compiled a report for Benbow’s defence team.
He found that McGrath didn’t use much power but had regular patterns in his electricity consumption. After looking at all the data, he told the court today that his conclusion was that “Mr McGrath was home, definitely home, until 9.30am” on the day he vanished - May 22, 2017.
Beatty said the data showed that by 5pm there was “definitely not” anyone inside the house.
However, further information provided by the Crown during cross-examination altered some of his earlier statements, he said.
Earlier information said load control was occurring in the morning with the hot water at McGrath’s home turning on at 9.27am. The new information said it was 9.11am. This meant the 1kwh could be either caused by a heater or the hot water cylinder.
“That one kilowatt could be accounted for by Mr McGrath being home or not being at home and you can’t say,” Crown prosecutor Barnaby Hawes said.
“That’s correct,” Beatty replied.
If the morning power spike was due to the hot water, then he believed someone had to be home to account for power consumption between 11.30 and about 12.30pm.
Hawes earlier said they had been provided his report in January this year.
In it, Beatty had included a disclaimer that was not mentioned during his evidence. Hawes asked him to read it aloud for the jury.
“This opinion is my personal opinion on observations of the electricity consumption at 53 Checketts Avenue, Oaklands, Christchurch,” he said in the report’s disclaimer.
“The low consumption and the absence of electricity consumption in general does not indicate a property is vacant. A property not consuming electricity or consuming very small amounts of electricity could be occupied...
The trial is ongoing at the High Court in Christchurch. Photo / Kai Schwoerer, Stuff, Pool
“I caution anyone from drawing conclusions on vacancy using electricity consumption as the sole reference point.”
In his report, he also stated that electricity consumption on its own “is not a good indicator if a premises is being occupied or not, particularly when consumption is low as a premises may be occupied with low or negligible consumption occurring”.
He agreed with Hawes that some care needs to be taken with power consumption data and its interpretation over occupancy.
Benbow claims his long-time friend never showed up to help him move the sleepers at 9am as arranged the day before and denies having anything to do with his disappearance.
The Crown claims Benbow shot him dead and got rid of his body, just weeks after telling a counsellor that he wanted to “annihilate” McGrath who was seeing his ex-partner Joanna Green.
Zane Greig, who looked after horses neighbouring Benbow’s property, said he never noticed anything out of the ordinary on May 22, 2017.
But today he said he was never spoken to police during the investigation, only a private investigator later on.
Under cross-examination by Crown prosecutor Claire Boshier, however, it transpired that a police officer phoned him on June 9, 2017.
During that conversation, he told police that he took horses out between 7am – 8am most days.
Michael Scarlett, who has lived at Checketts Ave “pretty much all my life”, was living in a sleepout when around 3am on Monday, May 22 he heard raised male voices coming from the street.
After lying there listening for 15-20 seconds, he got up to investigate and heard a car take off and “scream down the road”.
He went back to bed and later when police cordoned off McGrath’s nearby house, told police officers.
Scarlett was “100 per cent positive” the noise was coming from outside McGrath’s house.
Benbow’s lawyers earlier warned the jury of “investigative bias” and “tunnel vision” from police early in its investigations who they claim were trying to find evidence to support their case.
While the Crown accepts there is no body, no murder weapon, and little forensic evidence in the case, it says there is a strong circumstantial case consisting of many threads that, when taken together, show Benbow is guilty of McGrath’s murder beyond reasonable doubt.
The trial, before Justice Jonathan Eaton, continues.
