A 14-year-old girl was sexually assaulted on a bus from Dandenong to Doveton last month.
Police are appealing for help to identify the man responsible and believe the incident could be linked to an assault in Carnegie late last year.
In that case, a 21-year-old woman caught a train to the city from Murrumbeena about 5pm on Sunday 20 November.
A man boarded the train at Carnegie Railway Station and sat next to the victim before sexually assaulting her between the Carnegie and South Yarra railway stations.
Police believe the offender got off the train at Flinders Street Station.
They believe the same man followed a 14-year-old girl from Dandenong Railway Station about 3.50pm on Thursday 16 February.
He boarded the same Route 845 bus and sat next to her before sexually assaulting her.
Police believe he got off the bus at Linden Place, Doveton.
On Friday 24 March, Transit Crime Investigation Unit detectives released images and CCTV footage of a man who might be able to assist with their inquiries.
He is described as aged in his early 50s with a medium build, dark skin and greyish facial hair.
He was wearing brown pants, a brown shirt and a light-coloured hat, and was carrying a back pack.
Call Crime Stoppers on 1800 333 000 or submit a confidential report to www.crimestoppersvic.com.au with any information.
Police believe this man could help their investigation into two sexual assaults