Mr Wu's widow, Yan Yang, gave evidence for the Crown yesterday to describe the couple's first dealings with Wang.
A mutual acquaintance had pressed her husband to meet Wang to do business together, Mrs Yang said.
In late 2007, the couple agreed to attend a grand party put on by Wang in Helensville, spanning tennis courts and featuring live music.
"I got quite a clear impression of him," Mrs Yang said.
"He appeared quite polite, humble and very successful."
The appearance of great riches had attracted people to him, she said. Wang's wife, Michelle Chen, had been a visible hostess at the party.
Then she said Mr Wu and Wang began meeting each other periodically to discuss business, particularly in real estate, with Mr Wu initially buying a piece of land from Wang. In 2008, Wang came to Mr Wu asking for a loan of $125,000, Mrs Yang said.
She said Mr Wu agreed - but never saw his money again.
During the next three years, Mr Wu persisted - and failed - to get Wang to pay, and he discovered other people who had also run into financial strife with Wang, Mrs Yang said.
She said Mr Wu and some other complainants began meeting over dinners as Wang became the target of a Serious Fraud Office case.
Among those with grievances against Wang was Mr Zhong, the other man found dead in Mt Albert.
They had gone to the mansion last year as agents for Wang's wife, who had separated from Wang and returned to China, Mrs Yang said.
The property was owned by the estranged wife's trust and she wanted Wang out.
She had offered to pay Mr Wu if he served a trespass notice on him, Mrs Yang said.
"That was the deal between Michelle [Chen] and Michael [Wu]," she said, though she did not know how much money had been promised.
Both men then confronted Wang at his home in Mt Albert.
A virtual tour of the crime scene was presented to the jury by Environmental Science & Research staff yesterday.
Mr Zhong's primary wound was in his back, where a knife had punctured a lung, Crown prosecutor Kevin Glubb said.
Mr Wu was found with 23 knife wounds at the foot of a bloody set of stairs, Mr Glubb said. At the top of the stairs was the lounge where blood stains marked the struggle on the floor. Two knives lay nearby.
The trial continues today.