Watch William Sandeson's interview with Halifax police

The jury in the first-degree murder trial of Dalhousie University student William Sandeson has seen what are believed to be the last images of Taylor Samson while he was alive.

Sandeson is accused of killing Samson, a fellow student, in August 2015.

Video that police retrieved from a home security system Sandeson had installed at his apartment in south-end Halifax was played Thursday in Nova Scotia Supreme Court.

The system included a camera aimed at the hallway outside his second floor apartment, a camera pointed down the stairwell and a third camera overlooking the parking lot outside.

The video police collected was taken the night of Aug. 15, 2015. It shows Sandeson heading up the hallway, then returning a short time later with Samson in tow. Samson can be seen carrying a large black duffel bag. Court has been told that bag contained 20 pounds of marijuana, which Sandeson had agreed to buy for $40,000 cash.

There is no video showing Samson leaving the apartment and his body has never been found.

During his second round of questioning at police headquarters, Sandeson offered an explanation for Samson's disappearance. He said two other men were in the apartment to confront Samson.

"Just to scare him out of dealing," Sandeson tells the officer questioning him, according to a video of his interrogation played for the jury.

When asked why, Sandeson adds: "I know he owed money."

Sandeson tells the officer that the two men wore full bodysuits that concealed their faces. They told him to go into his bedroom and shut off the video security system. He said when he did, he heard a shot.

"They put Taylor in the bag with the weed," Sandeson tells RCMP Const. Jody Allison.

"How do you know that they put him in the bag?" Allison asks.

"They left the bag there," Sandeson replies.

Sandeson said the two men then picked up the bag by each end and left, taking Samson and the drugs with them.

As the interrogation nears the end, police tell Sandeson that evidence they've recovered from his apartment leaves holes in his story. That evidence includes the video showing Samson and Sandeson together in the hallway. Sandeson had initially told police that Samson failed to show up that night.

The jury was shown additional security video from Sandeson's apartment, including images of Sandeson making several trips carrying bags and boxes. The video shows him loading those objects into the trunk of his car.

As the interrogation ends, the officers tell Sandeson he's being charged with murder. They seize his clothes and lead him out of the interview room.

When the trial resumes Monday, the defence is expected to begin its cross-examination of the lead investigator in the case.

CBC's Blair Rhodes live blogged from the courtroom.