CCTV footage provided the key to cracking a love triangle which came to a bloody conclusion on a South Auckland road, the Crown says.
Gurjinder Singh, 27, is on trial with Amandeep Kaur, 32, in the High Court at Auckland for the murder of 35-year-old Davender Singh - Kaur's husband.
The Crown said the defendants had begun an affair months before the victim's throat was slit as he sat in his car on a Papatoetoe road in August last year.
But the pair's respective spouses had found out about the romance, which had blossomed while they worked together at Sistema Plastics in Penrose.
Between May and July, Kaur and Gurjinder Singh's phone records showed they had exchanged more than 130 phone calls and 1000 text messages.
The electronic contact stopped when the affair was discovered but Crown prosecutor Natalie Walker said their communications continued in the form of hand-written notes.
Most importantly, the Crown said the plan to murder Davender Singh was clearly apparent through those letters.
"Please do something, my love," Kaur said in one.
"Do you have anything we can use to kill him?" she allegedly asked in another.
On August 7, 2014, Davender Singh picked Kaur up from work and stopped on Norman Spencer Drive near the Manukau Events Centre.
Ms Walker said "grainy" CCTV footage showed the car pull up followed, minutes later, by that of Gurjinder Singh.
Nine minutes later he allegedly drove away and the Crown said Kaur "deliberately" waited three minutes before calling for help.
And it was a relative she contacted rather than emergency services.
When interviewed by police, Kaur said a stranger had approached on foot, stolen her husband's phone and stabbed him in the neck before fleeing.
Critically, for the Crown case, upon showing her the video footage of the two vehicles she changed her story and named Gurjinder Singh as the attacker.
Ms Walker said Kaur initially denied they had had an affair before admitting the fact.
Her co-accused was promptly brought in for questioning but denied any existence of a relationship or his presence at the scene, Ms Walker said.
When presented with evidence, his story also changed and he asked to speak to Kaur.
With the warning that what they were saying would be recorded, police facilitated the request.
Ms Walker said initially they offered to take the blame but by the end were pointing the finger at each other.
Gurjinder Singh said Kaur had struck the first blow and said she held her husband's hands down at one stage.
A knife - which was shown to the jury in a plastic box today - was found wrapped in a towel and some bloody clothes under a plastic sheet in Gurjinder Singh's garage, the Crown said.
Forensic testing allegedly found both his DNA and that of the victim on the weapon.
"The Crown does not have to prove which defendant was wielding the knife when Davender Singh was fatally stabbed ... the shared common intention to kill is enough," Ms Walker said.
"This was not a spur-of-the-moment act, this was an intentional killing."
Kaur's lawyer Sanjay Patel said it was accepted by his client there was an affair and also that there had been discussions about killing Davender Singh.
But he said when the killing took place the defendant and her husband had reconciled and he had forgiven her for her indiscretions.
She had totally withdrawn from any potentially criminal acts, he said.
However, that explanation was in direct contrast to that of Gurjinder Singh.
His lawyer David Niven denied his client had any knowledge or intention regarding a plan to kill on that day, nor was he at the scene when the fatal wound was inflicted.
He told the jury there would be extensive forensic evidence during the trial and foreshadowed challenges to the credibility of some of the DNA and finger-print assessments forwarded by the Crown.
"The defence suggests that once all the evidence is before you, the situation is not nearly as straightforward as the Crown is suggesting," Mr Niven said.