He said that in Brazil those who could prove neurological disturbance due to drug abuse could get a sentence of treatment at a medical centre rather than prison.
But proving his theory may be hard work.
Police in Macapa did not do the tests necessary to show that Colares had drugs in his system when he and his gang of water rats robbed Sir Peter's boat on December 5, killing the captain, knocking another crew member unconscious, almost fatally shooting a third and terrorising and robbing the rest.
But in court on Monday a woman who said she was Colares' cousin and sister of another robber, Jose Irandir Colares Cardoso, known as Junior, said her cousin and brother both came from middle- to upper-class families.
The Herald has been unable to speak to Colares' mother but one source who has spoken to his aunt said she had suffered a breakdown after her son's arrest for Sir Peter's killing and had gone for treatment at a centre in Sao Paulo.
A poor family would not have been able to afford the air ticket or the treatment.
Colares' cousin said she did not know him well as the families lived far apart.
But her brother had completed his high school education and his involvement in crime had shocked the families.
"They have a very Catholic family and they try to find a reason but they can't," she said through an interpreter.
Asked if her cousin was really a drug addict, she clammed up, refusing to confirm or deny this.
Mr Nielsen said claims that the prisoners had been tortured were definitely true and he showed the Herald a picture of Junior with vicious-looking bruising to his buttocks.
He said Junior's hands had been handcuffed to his feet, a plastic bag put over his head and he was beaten with a bat.
Colares was also tortured, he said. Wood inside a towel was used to beat him so it would not leave marks.
Mr Nielsen said the civil police had done this crime and were being investigated.
In Brazil, there is a bewildering array of levels of police.
At the top is the federal police, who investigated the Blake killing, then the state police, followed by military and civil police. These are followed by another force called the municipal police.
Mr Nielsen apologised for defending Colares but said his client had stolen to buy drugs. But he still had rights and these rights had to be defended.
Mr Nielsen said he had taken on Colares' case for free and had provided him with the clothes he had worn in court on Monday.
Mr Nielsen said he personally felt for New Zealand.
Sir Peter had been a huge personality, like motor racing legend Ayrton Senna, whom Brazil had mourned when he died, and soccer legend Pele.
"They are not members of a nation, they are world figures. Our nation has suffered with yours, just how we felt when we lost Ayrton Senna."
Peter Blake, 1948-2001
