Samuel Fane's partner, Sarah Lee Tarei, 25, is also on trial defending a charge of being an accessory after the fact to the alleged murders by assisting Samuel Fane to enable him to avoid arrest between February 11 and 14 last year.
The Crown alleges Samuel Fane, armed with a shotgun, and his late older brother Anthony Fane, with a .22 cut down rifle, carried out the murders.
Police found Lasslett and Littlewood's bodies inside a converted shed on Lasslett's rural property when officers arrived about 8.05pm on February 11, 2020, Pollett said.
She said the Fane brothers were captured on CCTV footage topping up Tarei's Blue Ford Territory at the BP service station in The Lakes on February 11.
At 7.18pm the same vehicle was also captured on a private CCTV security camera travelling to Lasslett's property.
Lasslett's security camera system also captured the blue Ford Territory driven by Anthony Fane with his brother in the passenger seat arriving at 7.29pm that day.
Both men got out of the vehicle parked at the top of the driveway and made their way to the converted shed dwelling and carried out the shootings, the Crown argues.
Pollett said as the pair left the address in their vehicle they also allegedly shot at another man running from the property and they were "out of there" by 7.39pm.
After the alleged shootings Samuel Fane sent a text message to Tarei asking her to pick him and his older brother up at Waitakaruru near Ngātea, she said.
The trio then headed back to Auckland, the jury heard.
Pollett said on the morning of February 12, Samuel Fane and Tarei packed their car and drove to her brother's home in Hamilton after she bought ferry tickets, then the couple headed to the South Island.
Samuel Fane asked his mother for money to help fund their "big road trip", and he and Tarei ended up in Christchurch.
She said Tarei assistance to her partner included helped Fane buy razor blades at a Christchurch supermarket so he could shave his head to change his appearance.
On Samuel Fane's arrest in Christchurch a shotgun was found inside one of the bags in the room where the couple was staying, Pollett said.
Meanwhile, Pollett said Anthony Fane believed that his partner Jessie Lee Booth,30, was having an affair with Paul Lasslett and feared his youngest child might not be his.
The pair had lived with Lasslett at his property some years earlier, Pollett said.
Pollett said two detectives making a welfare check on Booth on February 14 found her body in the lounge at her and her partner's Lynwood Place address in Brookfield.
The cause of death was from multiple crossbow bolt wounds to her head, she said.
Pollett said written statements read to the jury included evidence that police believed Anthony Fane had killed Booth using the crossbow and extra crossbow bolts he had bought about a month earlier.
Anthony Fane was fatally shot during an incident in Tauranga on February 13, 2020.
Pollett said during the trial the jury would hear evidence Anthony Fane told his mother he wouldn't hand himself into the police and he wanted to "go out in a blaze of glory".
She said that the law was clear that if two or more persons carried out a killing and helped each other in doing so they are equally culpable as parties to the murders.
Pollett also said Anthony Fane was "on a mission" to kill Paul Lasslett and Samuel Fane supported his older brother to carry out this plan.
She said there was ample opportunity for the brothers to develop their "grand plan" and for Anthony to try and urgently source ammunition for his rifle and another firearm.
Pollett said of the 104 witnesses in the trial, she expected about 30 would give evidence in person, and the rest would have their witness statement read to the jury.
Fane's defence lawyer Simon Lance made a brief opening statement to the jury.
Lance told the jury the Crown's opening address provided a "theory", but evidence needed to come from witnesses.
He said much of background to the case was not disputed but the defence would challenge some of the Crown witnesses' evidence.
"What evidence was there of a grand plan as the Crown suggests?... Anthony Fane was the person who was solely responsible for the death of his partner," Lance said.
"Samuel Fane had no knowledge of that and Anthony Fane was also responsible for the deaths of Paul Lasslett and Nicholas Littlewood.
"It was Anthony Fane who is responsible for what the Crown says was him going on his own rampage," Lance said.
He urged the jury members not to "jump to conclusions" and keep up an open mind until the end of the trial and they had heard all the evidence.
Tarei's lawyer Dale Dufty also gave a brief opening statement to the jury.
He said in order to find Tarei guilty the jury needed to be sure Samuel Fane was party to the alleged murders, that Tarei "provided some acts of assistance for the purpose of helping him evade arrest" and also that she knew he was an alleged party to murder.
"All of those elements are in dispute," he said.
"There is no evidence of her having knowledge of the shootings before she was told by the police nor any direct evidence she knew what happened at the Omanawa address.
"Even if you cobble all those facts together it is a long bow to draw ... Please keep an open mind until you have heard all the evidence."
The trial expected to take three to four weeks continues tomorrow.
