Detectives said they were investigating possible business connections of Kumar, who was probably murdered at Mildura, in northwest Victoria.
Kumar, 33, owned a labour contracting company.
Homicide squad detective Ron Iddles said Kumar went missing since a business deal meeting at the Mildura Library two weeks ago.
"He came here to meet someone, this was what he told someone, it was going to be a good deal for him and sadly I think he has met with foul play," said Iddles.
Kumar's blue Commodore car was located two days later outside the Mildura railway station.
In a separate incident, a man of 'Indian or Asian appearance' was stabbed at Melbourne suburb of Abbotsford following a brawl involving up to 10 men.