A man who strangled a stranger with a shoelace "for at least a minute" until he fell unconscious has been found guilty of attempted murder.

Key points: Abdolhadi Moradi remembers collapsing to the ground

Abdolhadi Moradi remembers collapsing to the ground His attacker David John Pearce ran off when other people intervened

His attacker David John Pearce ran off when other people intervened Prosecutors suggested the attack was racially motivated

David John Pearce approached Abdolhadi Moradi as he was walking along the Salisbury Highway in Adelaide's north in January last year.

Without warning, he attacked Mr Moradi from behind, strangling him with a shoelace with such force that he dragged Mr Moradi to the ground.

The attack stopped when a bus driver and other people intervened.

Pearce then ran off before being arrested a short time later.

In his 46-page judgment, Supreme Court Justice Sam Doyle described the attack as "brazen" and found Pearce intended to kill Mr Moradi.

"Mr Moradi was a relatively large and athletic man who was fighting for his life," Justice Doyle said.

"Yet the force was sufficient to prevent him getting his fingers between his neck and the shoelace, or otherwise breaking free.

"It is plain that it was not a fleeting episode of strangulation. I am satisfied that the strangulation continued for at least a minute, and probably closer to two minutes."

Mr Moradi told the court, through a Farsi interpreter, that he was unable to breathe as soon as the cord was around his neck and he remembered collapsing to the ground.

"When Mr Moradi regained consciousness he was dazed, for a few moments he was not able to see clearly and thought he was in a nightmare," Justice Doyle said.

Racial motivation 'a possible explanation'

The court heard Mr Moradi was born in Afghanistan and moved to Iran before moving to Australia.

During the trial, the prosecution suggested there was a possibility Pearce had wanted to carry out "a racially motivated 'show killing'".

However, Justice Doyle said he could not reach that conclusion beyond reasonable doubt.

Victim Abdolhadi Moradi in hospital after the attack. ( Supreme Court/SA Police )

"While there is some evidential basis for this suggested motive — given the appearance of Mr Moradi and the very public setting of the attack — I do not consider it appropriate to make a finding to this effect," Justice Doyle said.

"In my view, it would be speculative to do so. Again, I accept it is a possible explanation, but nothing more than a possible explanation.

"The evidence does not permit the identification of any explanation or motive for the accused's serious and brazen attack upon, and strangulation of, Mr Moradi."

Justice Doyle said police footage of Pearce during and after his arrest showed him looking "dazed and confused".

"The accused appeared exhausted, spending some of the time sitting on his haunches," Justice Doyle said.

"At times he appeared steady on his feet, but at other times he leant into the wall, and buried his face into the corner."

The court heard Pearce had a low concentration of methylamphetamine in his system at the time, consistent with "recreational" use, and was also dehydrated.

Justice Doyle said taking into account the unexplained nature of the attack and the fact that Pearce was "clearly affected at least to some extent" by his intoxication or dehydration, he was satisfied Pearce had formed the necessary mental intent to kill.

"I am satisfied that the prosecution has excluded any reasonable possibility that the accused was confused, delirious, psychotic or otherwise affected to the extent that he did not know and understand what he was doing when he strangled Mr Moradi, and the risk of it causing death to Mr Moradi," he said.

Pearce had pleaded guilty to a different charge of aggravated endangering life but that was rejected by the prosecution who successfully argued Pearce had intended to kill his victim.

Sentencing submissions will be heard on March 27.