A woman who took a photo of a man who allegedly indecently assaulted her on a Sydney train has been described as "clever and brave" by NSW Police.
The 19-year-old woman was allegedly attacked on a train travelling from St James to Auburn last August.
Her actions had been a great help to police with their investigations, Superintendent Brad Monk, commander of Police Transport Command northwest said.
"The lady who took this photo did so discreetly, she was very, very clever, very brave in what she did," he said.
"It has been extremely advantageous in our investigation."
Police Transport Command has launched Operation Artemis, and are appealing for information about multiple indecent assaults on Sydney trains and buses.
They would like to speak to a man of Indian Sub-Continental appearance, about 165cm tall, aged in his late 20s or early 30s.
An 18-year-old woman travelling by bus from Parramatta to Baulkham Hills in March and a 14-year-old girl travelling from Blacktown to Glenwood in May were also victims of alleged indecent assaults.
Superintendent Monk said it was unacceptable that people would be subject to attacks while commuting.
"There is no tolerance for any of these offences ... it's happening too frequently for anyone's liking
"For me to talk about three offences in particular is too many," he said.
Police arrested an alleged sex offender on Wednesday morning but said he was unrelated to the three cases.
"I can say this morning we have had some success in being able to identify and arrest one sex offender this morning," Superintendent Monk said.
"Operation Artemis is as much about preventing crime on public transport before it happens, as it is about investigating.
"Our officers are constantly patrolling and watching the public transport system, and make no apologies for getting in the face of people they believe are committing crimes."
