HALIFAX – The defence in the case of a Halifax university student accused of murder closed its case Tuesday, saying William Sandeson remains “confident” after weeks of testimony at the jury trial.Sandeson is charged with the first-degree murder of 22-year-old Dalhousie University student Taylor Samson, whose body has never been found.The Crown has alleged Samson was murdered in Sandeson’s south end Halifax apartment in the midst of a drug deal.Lawyer Eugene Tan says his client, who has taken an active role in his own case, has been “holding up very well” throughout the eight-week trial.“He’s very invested in his own defence. He knows the case extremely well,” said Tan outside of Nova Scotia Supreme Court on Tuesday.“You’ve probably seen him looking up things, passing notes to us, making references to specific pages of evidence and giving it to us. He has maintained his focus on this trial.”Closing arguments in the case will be presented Monday, with the judge expected to instruct the jury the following day.Tan said the defence will argue that the police investigation into Samson’s death was not adequate.He said police put their focus on Sandeson too early in the investigation without looking at other possible suspects.“There were a lot of leads that were presented, some of which we feel were substantive and should have been pursued,” said Tan.“At the end of the day we feel that in a lot of ways, there was a result that was sought and everything along the way was used to justify that result, to the exclusion of other possibilities.”Sandeson did not testify at the trial. Tan said defence lawyers did consider putting him on the stand, and that was an “open question up until today.”The trial heard DNA 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.It heard the medical student was deep in debt and under pressure from his parents about his spending in the weeks before he allegedly murdered Samson.The jury has also heard Samson was to sell Sandeson 20 pounds of marijuana for $40,000 the night of Aug. 15, 2015. Court has heard Samson was last seen alive on video that night, walking into Sandeson’s apartment shortly before 10:30 p.m.On Tuesday, Sandeson’s former girlfriend testified she smelled bleach when she returned to Sandeson’s apartment later that same evening.Sonja Gashus told the jury she had gone out to dinner with Sandeson, and was told by him she would need to leave his apartment for a period of time later that night — something she described as unusual.The recent Dalhousie graduate later testified that she believed Sandeson was conducting a drug deal.Gashus — who dated Sandeson for roughly eight months and is no longer with him — said she did not approve of Sandeson’s involvement in selling drugs, especially after he was accepted into medical school earlier that year.“I believed that it was him making a deal and he said that he was going to get out of the whole thing,” the 23-year-old woman told the jury of the night of Aug. 15, 2015, later saying she thought Sandeson was selling off his drug dealing business the night Samson disappeared.Gashus said she went to a friend’s home nearby and received a text message from Sandeson at around 12:30 a.m. on Aug. 16, 2015, telling her she could return to his apartment.She said she smelled cleaning products when she arrived there, but nothing else about his apartment was out of the ordinary. Under cross-examination, she told the Crown she didn’t see any blood, but told police the apartment wreaked of bleach.She said Sandeson had told her three people had arrived at the apartment to bid on his drug dealing business, and one of the individuals hit another individual and that caused him to bleed. She said that he told her the smell of cleaner was from him cleaning up the blood.Note to readers: This is a corrected story. An earlier version said the judge would instruct the jury Tuesday.