Accused murderer Robert Xie paid more than $100,000 on funerals for the Lin family and then allegedly told a prison inmate the spending would help his defence.
This, along with murder weapons and fixing evidence were among the topics the inmate claims Xie discussed with him in the months after his arrest over the deaths of five family members.
The man, who can only be referred to as Witness A, admitted that getting out of jail was at the forefront of his mind when he decided to feed information to police about the new inmate at Long Bay from 2011.
Xie, who arrived in prison in May that year, initially kept to himself, Witness A said.
But slowly he began opening up after a ping pong game in which Xie "wiped the floor" with Witness A.
"It (the relationship) evolved into one where we would speak daily," Witness A told the Supreme Court jury on Monday.
On the funeral payments for the slain family, Xie allegedly said: "My wife wanted to do it ... and this also looks good for my defence".
The crown says Xie had been motivated by bitterness when he crept into his brother-in-law's Epping home in Sydney's northwest on July 18, 2009 and attacked the Lin family with a hammer-like weapon.
The battered bodies of newsagent Min Lin, 45, his wife Lily, 44, her sister Irene, 39, and their sons Henry, 12 and Terry, nine, were found later that day.
Xie has pleaded not guilty.
During one conversation about the case, Witness A alleged Xie asked him, "How would it look if the murder weapon turned up during the middle of my trial with someone else's prints on it?"
Xie also allegedly remarked "you can never clean a hammer properly because the metal is porous".
Witness A told the court Xie was "very concerned" about a DNA report and discussed using the inmate's "friend" to "fix evidence".
After Witness A said it would cost $200,000, Xie allegedly replied: "I want to wait to see DNA report".
On another occasion Witness A claimed Xie showed him how to push on a pressure point in the neck which could "stop the heart" or at least slow it down.
Xie also said his wife's parents never liked him and compared him unfavourably with Min, Witness A said.
"They think he's very smart businessman ... but this business is rubbish," Xie allegedly said.
At the time the pair met, Witness A was serving time for drug supply and driving while disqualified.
Throughout his life he has spent more than 18 years behind bars for a variety of offences, including armed robbery, larceny and assaulting police.
The trial continues.
