A Canadian pig farmer accused of being the country's worst serial killer has pleaded not guilty to the murder of 27 women sex workers and drug addicts.
Investigators spent months combing the Vancouver farm
Robert Pickton is accused of killing the women over a 25-year period.
Mr Pickton, 56, was arrested four years ago when dozens of police swept onto his farm in the suburbs of Vancouver.
Investigators, searching for evidence in the cases of 60-70 sex workers missing from the area, spent months sifting the soil on the farm.
Police say they have found the DNA of at least 31 of the missing Vancouver women at the farm, and evidence to prosecute 27 of the cases.
One of the 27 has still not been identified.
The police have been criticised for not taking the disappearances very seriously at first, but now there is no question that this is a major case, the BBC's Ian Gunn in Vancouver says.
Since the arrest of Mr Pickton in 2002, the scale of the case has slowly grown, following a painstaking and lengthy search of the land and farm buildings.
The trial began in a small suburban courthouse in New Westminster, British Columbia, crowded with the family and friends of the victims, most of whom were native Indians.
Supporters held a rally outside the courthouse, beating traditional aboriginal drums to remember the dead.
Such is the complexity and volume of evidence that the court is now expected to hold several months of hearings about what evidence can be presented at trial, says our correspondent.
Jury selection and proper testimony are only expected to begin much later this year.
A court ban prevents journalists from reporting any of the evidence until a jury has been chosen.