HALIFAX -- A Halifax jury watched the last known sighting of a Dalhousie University student Thursday -- Taylor Samson walked into his alleged killer's apartment, but was never seen walking out.

The surveillance tape was shown at the first-degree murder trial of medical student William Sandeson, who is accused of killing the 22-year-old during a drug deal.

The video captures Samson following the accused into Sandeson's apartment on Aug. 15, 2015, carrying a big black bag.

Samson had brought 20 pounds of marijuana to sell to Sandeson.

The 24-year-old told police Samson was shot in the back of the head by two men dressed in black who came into his apartment. Sandeson said he cleaned up after they left, and turned off his surveillance system at their request.

The surveillance tape never shows Samson leaving the apartment, but Sandeson is seen carrying garbage bags and other items to his vehicle over the next few days.

Detective Constable Roger Sayer, an investigator on the case, testified Thursday that Sandeson texted Samson, "I'm on my way down," right when he is seen on video walking down a white hallway outside his apartment to go meet Samson.

The jury later watched Sandeson walk out of his apartment several times, once completely shirtless, leaving an item on a shoe rack in the hallway.

Surveillance footage captured Sandeson's actions on subsequent days as well.

On the morning of Aug. 16, the day after Samson went missing, surveillance footage shows Sandeson leaving his apartment early in the morning with his girlfriend. It also shows him putting items and bags into the back of his car.

On Aug. 17, the footage shows Sandeson carrying more items out of his apartment, including a black Dalhousie backpack and a large white box.

"These items were seized, and found to be containing what was 20 pounds of marijuana," said Sayer about these items.

On Aug. 18, he is seen carrying out full garbage bags with gloves on his hands and placing them in the back of his car.

He was charged with murder the next day.

Sayer told the court the investigation is still ongoing because Samson's body has not been found.