"While the train was in transit and entered the city loop, the woman noticed a light shining from the man's crotch and realised he had a torch and mirror between his legs so he could look up her skirt," Detective Sergeant Mick Ashby said.
"She has challenged the man and moved to the doors as the train left Parliament station and got off at the next stop at Melbourne Central where she has lost sight of the man," Sgt Ashby said.
"This is obviously very concerning.
"As far as we are aware, he didn't have any electronic recording device but the set-up was more elaborate than some we have seen.
"It seems the briefcase was in place to hide the torch and mirror."
Police have released images of a man who they believe may be able to assist them in their inquiries and hope someone will recognise his distinctive features and call Crime Stoppers.
The man is described as Caucasian in appearance and aged 50-60, with dark hair and a bushy beard that is greying.
He was wearing a dark broad-brimmed hat, dark-coloured suit jacket with matching pants and a light, blue-coloured button-up shirt.
It is believed the man boarded the City Loop train at Richmond station on Monday, November 26, after commuting inbound on the Sandringham train line.
heraldsun.com.au 7 Jan 2013
Looks hauntingly familiar. Rabi Ashkenazy from Caufield?