Only one of four policemen charged with assault over the death of a Brazilian student who was tasered in Sydney has been found guilty.

Roberto Laudisio Curti died in March 2012 after being tasered 14 times - seven times within 51 seconds.

The 21-year-old had taken LSD when he jumped the counter of a convenience store in Sydney's CBD and stole some biscuits.

A witness called triple-0 and the operator mistakenly recorded the report as an armed robbery.

Up to a dozen officers chased the Brazilian student on Pitt Street, but he managed to get away twice.

The pursuing officers said he was violently thrashing around when they tried to hold him down.

Four of the policemen involved were charged: two with common assault and two with assault occasioning actual bodily harm.

The policemen - Senior Constable Damien Ralph, Senior Constable Eric Lim, Leading Senior Constable Scott Edmondson and Constable Daniel Barling - were at Downing Centre Local Court on Tuesday morning to hear their verdicts.

Magistrate Clare Farnan found only one policeman guilty - Senior Constable Ralph - and his assault charge related to the use of capsicum spray, not Tasers.

"While I accept that in the heat of the moment Mr Ralph may have thought it appropriate to continue to use the third bottle of OC (capsicum) spray... it is obvious that it was not," she said.

Coroner's findings brought matter to court

Mr Curti's cause of death was inconclusive, but it was the damning findings of a coroner nine months after his death that led to the matter ending up in court.

In November 2012, coroner Mary Jerram said the actions of police were reckless and excessive, and constituted an abuse of police power.

She said they "threw themselves" into the confrontation "like schoolboys in Lord of the Flies".

But on Tuesday Magistrate Clare Farnan found the other three policemen - all of whom deployed their Tasers on Mr Curti - not guilty.

The court heard the Brazilian student was delusional and paranoid when he ran from police who mistakenly believed he had held up the convenience store.

One officer issued this over the police radio: "This bloke's still playing up, we'll wait for ambos to come, he may have to be tranquillised or something of that nature."

But eight minutes after the last Taser discharge, police realised Mr Curti had no pulse.

Referring to the chaotic chase as the "agony of the moment", Magistrate Farnan said she believed Senior Constable Edmondson when he said he did not realise his colleague and co-accused Constable Barling had already fired his Taser on the student.

"Both officers reacted at the same time to Mr Curti's increased movement and resistance to being restrained," she said.

Magistrate Farnan accepted the evidence given by Senior Constable Lim, who said he did not realise Mr Curti was already handcuffed when he deployed his Taser on him.

That left only Senior Constable Ralph with a guilty finding. His barrister Ray Hood stayed behind in court to argue that a conviction should not be recorded.

"He's been a troubled soul since this happened," he said.

"He now has the difficulty of understanding that his conduct on that day was beyond what the courts consider reasonable."

The magistrate accepted that Ralph has suffered psychologically since Mr Curti died and she agreed not to give him a criminal conviction.