Brittney Lee Irving, 24, was last seen leaving a Kelowna motel in April 2010. Police say she was taking a large amount of marijuana to a drug deal.
Her body was found with four bullet wounds in a wooded area south of Kelowna on May 25.
Joelon David Atish Verma has been charged with first-degree murder and robbery in connection with her death.
On Wednesday, Irving’s friend Cassandra Berard wept as she talked about the drug-fuelled lifestyle the two were both caught up in.
Berard says they were both heavily into drugs before Irving's death, saying she smoked crack cocaine while Irving took Oxycontin.
She told the court Irving paid for much of her drug habit by running marijuana grow operations.
Berard testified Irving used multiple cell phones to speak with her drug contacts.
Crown lawyers say Verma was one of those contacts.
Prosecutors allege Verma killed Irving and left her body in the woods after she sold him nearly 25 kilograms of marijuana.
Verma has been in custody since his arrest in June 2010.
The jury trial is expected to last six weeks.