Cricket Australia has confirmed India's players were subjected to racial abuse during the third test at the SCG but cleared the six spectators who were taken from their seats and questioned by police at the ground.
Problems first emerged at the close of the play on the third day when a group of senior India players were seen in conversation with the umpires as they left the field.
On the fourth day, play was held up for about 10 minutes after Siraj approached an umpire to voice his concerns before police stepped in to take six male fans from their seats.
"CA confirms that members of the Indian cricket team were subjected to racial abuse," CA head of security and integrity Sean Carroll said in a statement.
"CA's own investigation into the matter remains open, with CCTV footage, ticketing data and interviews with spectators still being analysed in an attempt to locate those responsible.
"CA's investigation concluded that the spectators filmed and/or photographed by media in the Brewongle Stand concourse at the conclusion of the 86th over on day four of the test did not engage in racist behaviour."
CA said it had submitted its report on the investigation to the ICC. The board added that it was awaiting confirmation from police that they had completed their own investigation.
Both Siraj and Ajinkya Rahane, India's stand-in captain for the final three Tests in Australia, said that the on-field umpires had given them the choice of leaving the field in Sydney while the authorities were dealing with the spectators, but Rahane refused.
"What happened in Sydney was very bad and not acceptable at all," Rahane told the Indian Express this week. "When we go overseas, fans abuse opponents to cheer up the home team. But when people are abusing you based on the colour of your skin and hurling racial slurs, that are not acceptable. My message [to the authorities] was: Those who racially abused the players, get them out of the ground. We will not leave the field. Until you are ejecting them, we are not playing."
Speaking shortly after the incidents at the SCG, R Ashwin said abuse from the crowds had been a regular feature of his visits to Sydney.
"This is my fourth tour to Australia and in Sydney, especially, we have had a few experiences even in the past," he said. "I think one or two times even the players have reacted and got into trouble in the past, and that's not because of the player, it is actually because of the way the crowd has been speaking, especially the people close to the boundary edge."
"They have been quite nasty, they have been hurling abuses as well, but this is the time they have gone one step ahead and used racial abuse."