Yuri Nilolaevich Vergiles, a businessman in his early 50s, had died while being treated at a private hospital in Anjuna village last week.
The death, which was earlier registered as "unnatural" is now being probed after the deceased's friend and business partner Yulia Yaskova wrote to police, suspecting foul play.
Deputy Superintendent of Police Bousette Silva, who is heading the investigation, said the postmortem of the deceased was carried out but the cause of death is yet to be confirmed.
Forensic experts from Goa Medical College and Hospital near here, a state-run facility, have sent viscera for chemical analysis to Regional Forensic Science Laboratory in Surat, Gujarat.
Police said the cause of death would be known only after getting the chemical analysis report.
Russian Consulate's representative in Goa, Vikram Varma, said they have sought details from police about the death.
"We will have to wait for viscera report before deciding further action," Varma said.
However, the family members of the deceased in Moscow have taken a contradictory stand asking police not to conduct the postmortem, claiming that Yuri was an alcoholic.
"We were informed that he (Yuri) was deep in problems like alcohol and drugs...We do not insist on postmortem...He died because of too much of alcohol and drugs," Kuchuk Valeriy, who claims to be one of the family member of Yuri, said in an email to the police.
The family has also questioned the credentials of Yulia, the girl who wrote to police raising suspicion about the death.
Police have said they will also probe the authenticity of the email.
Around 1.3 million Russians arrived in the state last financial year, making it the largest international community to visit the coastal state.
There are more than 500 Russians living in Goa since a long time after their arrival on a business visa.
