Three years after the alleged murder of Gemahl Maika at Glen Alpine in 2011, the accused gunmen Googled the shooting and showed it to an undercover police officer.

"I have my credentials...the last one was a message...left for everyone to see," Maximillian Mazzilli allegedly told the officer at a meeting at a Tweed Heads hotel in May, 2014.

"No drama is too big for me...."

Less than two months after allegedly describing the details of the shooting, Mazzilli was arrested in a western Sydney car park and charged with murder.

Mazzilli, who has pleaded not guilty and is on trial in the NSW Supreme Court, is accused of shooting Mr Maika in a plan allegedly hatched by Luke Sparos, who he had shared a wing with at Long Bay jail.

It is alleged Sparos wanted retribution for Mr Maika giving evidence against him in his drug importation case.

Sparos was due to face trial for the drug charge in May, 2011, a month before Mr Maika was killed.

"It is alleged in this trial Mr Sparos instigated the murder," Crown prosecutor Craig Patrick SC told the court on Monday.

"He was determined to silence a witness in the case against him."

However, Sparos's defence argue Sparos had already offered to plead guilty to the drug charge and had hopes for a stay on his case so the "last thing he wanted" was Mr Maika's killing.

Sparos' wife, Christine Saliba, who has pleaded not guilty to being an accessory before the fact, is accused of helping in the preparation of the alleged crime.

Sparos' brother-in-law, Anthony Saliba, has also pleaded not guilty to murder.

He is accused of acting as a "conduit" between Sparos and others involved in the planning.

All four faced trial in the NSW Supreme Court on Monday.

Mr Maika was killed when he arrived at his Glen Alpine home on April 6, 2011, after finishing a class at Campbelltown TAFE.

He was shot four times in the upper body and once in the head.

Mr Patrick said Mr Maika had given evidence, including in court and in three statements against a number of co-offenders, including Sparos, as part of a drug importation case.

As a result, Mr Maika wasn't charged.

It is alleged Sparos, while in jail, used code to speak on the phone to plan Mr Maika's murder, including sourcing a gun and organising payment.

​Sparos and Mazzilli had both been in wing 13 of the Long Bay Correctional Centre before Mazzilli was released.

The court heard Sparos spoke to a person known only as "witness b" and said he "desperately needed a gun".

"I'm running out of time, the bloke is ready to go," Sparos allegedly told the witness, who failed to source a firearm.

During the police operation with Mazzilli in 2014, he allegedly told an undercover officer how he took cable ties to Mr Maika's house to "tie up the whole family".

"...but there were girls, little girls there and shit," he allegedly told the officer.

Mazzilli told the undercover officer when Mr Maika arrived home, he said his name, Mr Maika turned around and "pow, pow, pow".

However Mazzilli's barrister Linda McSpedden said her client got factual references to the shooting from newspaper publications and talk in jail.

She said it was denied Mazzilli had any knowledge of any plan to shoot Mr Maika and he "absolutely denied" any responsibility for it.

The trial continues.