A man accused of stabbing two brothers more than 20 times in their Sydney home allegedly disguised himself as an old woman before carrying out the killings.
Giuseppe Di Cianni has pleaded not guilty to murdering Mario Frisoli, 52, and Albert Frisoli, 56, who were found dead in their Rozelle home, in Sydney's inner west in May 2009.
Josephine Pintabona has also pleaded not guilty to the Frisoli murders and to the alternate charge of being an accessory after the fact.
In his opening address at the NSW Supreme Court on Monday, crown prosecutor Mark Hobart SC said Di Cianni and Albert Frisoli had a history marked by "animosity and violence".
The pair were co-directors of a construction company but the relationship soured after Di Cianni was diagnosed with cancer in 2000.
Believing Albert was defrauding him, Di Cianni began threatening him and launched civil proceedings against him, Mr Hobart alleged.
In response Albert had made a number of Apprehended Violence Orders (AVOs) against Di Cianni.
Mr Hobert said on the night of the stabbings a neighbour saw a "little old lady" walking up to the door of the Frisoli brothers' home.
"The little old lady was the accused, Di Cianni, dressed in woman's clothing," Mr Hobart said.
Once inside, Di Cianni allegedly stabbed Mario, who was alone, 21 times.
"Although Mario wasn't the main object of Di Cianni, he killed Mario anyway ... in the most brutal manner," Mr Hobert said.
When Albert returned home two hours later he was stabbed 27 times.
Pintabona allegedly drove Di Cianni to and from the scene.
A scarf found at the scene, and used as part of Di Cianni's "disguise", had DNA evidence "consistent" with Pintabona, Mr Hobart said.
But Di Cianni's barrister Peter Bodor QC said his client, who was extradited from Italy to face the charges, had consistently denied his involvement.
He said police had come up with a "theory" and then moulded the investigation to support it.
Meanwhile, David Dalton SC said there was no evidence that either Pintabona or her car was seen at the scene.
The trial continues.