The girlfriend of a slain Halifax university student whose body has not been found testified Monday at the first-degree murder trial of the accused.

Mackenzie Ruthven is believed to be one of the last people to see her boyfriend, Taylor Samson, alive.

William Sandeson, who also attended Dalhousie University, is charged in Samson's death.

Ruthven told the seven man, seven woman jury hearing the case in Nova Scotia Supreme Court that Samson left his apartment around 10 p.m. on Aug. 15, 2015.

She said Samson told her he wouldn't be long and left his wallet and keys behind. She never saw him again.

Victim left home with 20 pounds of marijuana

Ruthven said Samson was carrying a large black duffel bag that night, which she later learned contained 20 pounds of marijuana.

Ruthven said she knew her boyfriend dealt drugs but she testified he tried to shield her from that activity. She said she'd never seen him deal that quantity of drugs before.

Under questioning by one of Sandeson's lawyers, Ruthven confirmed that Samson used cocaine on occasion.

The defence also questioned Ruthven about Samson's autoimmune liver disease.

She said the night he disappeared, he hadn't taken his medication in a couple of days. She said she was concerned when he went long periods without taking what was supposed to be daily medication.

Police sergeant wraps up testimony

Before Ruthven took the stand, the defence finished questioning Sgt. Sandra Johnston of the Halifax Regional Police. She photographed Sandeson's apartment and all the items police seized from there in the course of their investigation.

The defence tested Johnston's memory of what she did during the investigation 20 months ago.

Johnston told the court she didn't photograph things she felt had no connection to the case. She said that included the contents of a garbage can police found in the kitchen of Sandeson's apartment. She said it was searched, but nothing useful was found.

The trial is expected to last 32 days. The Crown expects to call 40 witnesses.

Blair Rhodes live bogged from court.