Sweeney died at a hospital here on April 14, 2010, after becoming unconscious at a nightclub at Vagator, a beach village.
Police had then said that she died of a drug overdose, but her sister, Maureen, refuted the claim. Last week police reopened the probe and registered a case of murder.
Police sources said that Maureen would be called to India to give a statement.
"If she does not come, we won't travel to Britain. We will proceed with our investigation," a senior police official said.
Maureen had started a campaign in UK, calling for fresh probe, stating that a British coroner's report had mentioned that there was no trace of alcohol or drugs in the body; but there were 20 bruise marks. The first autopsy in Goa had been inconclusive, and there was another autopsy in UK.
Superintendent of Police (North) Vijay Singh told PTI today that the statement of forensic expert Dr Silvano Sapeco, who works with Goa Medical College and Hospital where the first autopsy was conducted, was recorded yesterday.
Singh, however, refused to give more information.
The statement of retired Police Inspector Manjunath Desai, who had conducted the probe in its initial stages, would also be recorded.