HALIFAX -- A Halifax university student is not a "criminal mastermind" and the Crown has twisted evidence in the case to fit its theory that William Sandeson murdered Taylor Samson during a drug deal, defence lawyer Eugene Tan told the jury Monday.

In his closing arguments, Tan said the Crown has attempted to make Sandeson look like a "calculated murderer who mapped out every detail," when evidence presented at the trial showed the opposite.

"They (the prosecutors) believe William Sandeson to be a criminal mastermind," Tan said before a packed courtroom at Nova Scotia Supreme Court, eventually asking the jury to acquit the 24-year-old man.

"Mr. Sandeson is not a criminal mastermind. He didn't think things through. He certainly didn't expect any of the things that happened to happen."

Sandeson -- who was slated to start medical school within a week of his arrest -- is charged with first-degree murder in the death of the 22-year-old Dalhousie University student, whose body has never been found.

Tan said the police and Crown have tried to make evidence fit their theory that Sandeson lured Samson to his south end Halifax apartment on Aug. 15, 2015 with a plan to shoot him and steal 20 pounds of marijuana.

"They have achieved results in their own mind and they are trying to fit everything else within that frame," he said.

Tan conceded there was a "violent incident" at the apartment that night, but said Sandeson maintains there was someone else who was also at the apartment.

He asked the jury to ask themselves a number of questions when considering the evidence, including why Sandeson would have kept his own video surveillance system running if he intended to kill Samson.

Court has heard Samson was last seen alive on video that night, walking into Sandeson's apartment shortly before 10:30 p.m.

Tan asked the jury to consider why, if Sandeson had carried out a pre-meditated murder, he would leave his handgun in a safe in his bedroom, and why he gave police text messages between him and Samson that described a drug deal?

Tan said evidence has shown Sandeson was aware his neighbours were home when Samson arrived at his apartment, and asked the jury why someone who planned to carry out a murder would do so knowing there were people in the apartment next door.

He noted those neighbours testified Sandeson appeared panicked that night and was "incapable of forming words." Tan asked if someone who was planning a murder would act in that way after the fact.

Sandeson's former girlfriend testified at the trial that she smelled bleach when she returned to Sandeson's apartment later that same evening. But Tan noted that someone can be involved in cleaning up a crime scene without being guilty of murder.

He also suggested that police did not follow up on all possible leads in the investigation, and only looked at evidence that supported their theory, while handling evidence poorly.

The trial has heard the medical student was in debt and under pressure from his parents about his spending in the weeks before he allegedly murdered Samson.

Tan said the Crown will suggest Sandeson was in part motivated by money, but he noted Sandeson had more than $120,000 available to him on a line of credit, as well as a credit card and a chequing account.

"The question of financial motive just simply can't exist," said Tan. "You've got to reject that. There's no evidence whatsoever supporting it."

Sandeson -- who has closely cropped hair and was wearing a black sweater -- sat quietly during Monday's proceedings. He did not testify at the trial.

The Crown will deliver its closing arguments Tuesday. Judge Josh Arnold is expected to instruct the jury on Thursday.

The trial heard DNA matching Samson's profile was recovered from a bullet, gun, tarp, duffel bag and other items seized from Sandeson's Henry Street apartment in Halifax and his family's farm in Truro.