The trial opened on Monday of two Indian men accused of killing British teenage girl Scarlett Keeling in the popular resort state of Goa two years ago.
Federal investigators formally charged the men late last year over the death of 15-year-old Keeling, whose bruised and half-naked body was found on popular Anjuna beach in February 2008.
The trial began with testimony from prosecution witness Vishant Chopdekar, one of the first policemen to reach the scene. Both the accused men stood in the dock.
Keeling's mother Fiona MacKeown will be called to testify -- probably next week -- and a verdict is expected by the end of the year, lawyers said.
MacKeown waged a concerted campaign to get Indian police to treat her daughter's death as a crime rather than an accident, and has expressed anger that the two defendants were not charged with rape and murder.
Police allege that Keeling was given a cocktail of illegal drugs and dumped unconscious in shallow water where she drowned.
Two Goans, Samson D'Souza and Placido Carvalho, have been charged with culpable homicide, using force with "intent to outrage her modesty" and administering a drug with intent to harm.
Investigators have submitted a list of 72 witnesses to be examined by the court which will hold hearings three times a week in the state capital Panaji.
Keeling and her family were on a six-month holiday in India when she died. MacKeown left Keeling in Goa while she and her other daughters went on a trip to the neighbouring state of Karnataka.
There have been a series of high-profile crimes against foreigners in Goa which have prompted fears about the safety of tourists, as has the widespread availability of drugs, despite efforts by authorities to stamp out peddling.
Aggressive drug pushing remains commonplace at Anjuna beach, a resort in the north of the former Portuguese colony that has been a haven for travellers since the days of the hippy trail in the 1960s and 1970s.
Some 400,000 foreign tourists flock to the tiny state every year, attracted by its sandy beaches, sunshine and all-night parties.
In Britain, Keeling's mother is facing a possible jail term after admitting last month that she falsely claimed 19,000 pounds (29,000 dollars) in state benefits between 2005 and 2008.
The date for her sentencing has been postponed because her defence lawyer said she needed to attend the trial in India.
Before her fraud hearing, MacKeown said she was sceptical that the two accused men would be convicted.
"It's all for show," she said. "It's to show they're doing something about it. I don't think they'll ever convict the two of them."
MacKeown has repeatedly alleged a cover-up, saying police and politicians in Goa protect criminals and drug traders.