HALIFAX -- William Sandeson's lawyer is challenging the memory of a neighbour and friend who says he saw a bloody man in the medical student's apartment.

Pookiel McCabe said Tuesday he had two brief occasions to see the man, sitting motionless on a chair with blood on his back, as well as cash and a lot of blood on the floor.

Sandeson, 24, is on trial in Nova Scotia Supreme Court for the murder of 22-year-old physics student Taylor Samson. The jury has heard previously Samson had gone to the apartment to sell Sandeson 20 pounds of marijuana.

Defence attorney Eugene Tan showed McCabe and the jury police photos and surveillance video of the moments McCabe was in Sandeson's Halifax apartment on Aug. 15, 2015.

Tan suggested McCabe only briefly saw the bloody man, and that his view was obstructed by a friend.

Tan questioned him about a video from Sandeson's security system that showed McCabe and a friend going to Sandeson's twice that evening.

McCabe only looks in briefly on the first visit, while on the second he stands behind his friend outside the apartment.

"You're probably not going to see much more than the back of (your friend)," said Tan.

But McCabe said he saw a "guy sitting in a chair, lots of blood on him." The man was facing away from him, he said.

McCabe, who testified Monday he was close friends and track-and-field teammates with the accused, said he heard a loud bang coming from Sandeson's apartment across the hall and went over to see what happened.

Later Tuesday, the jury heard from three Halifax Regional Police officers who testified about their time guarding Sandeson's apartment on Aug. 18 while a warrant was being sought, and to search it for Samson.

Two of the officers said they saw Mackenzie Ruthven, Samson's girlfriend, outside a rooftop window leading to Sandeson's apartment.

They said McCabe also showed up looking to pick up bail money. He told them a female lawyer contacted him asking him to get money from the apartment, they said.

"McCabe seemed surprised we were there," Const. Justin McGrath told the jury.

McCabe left the building a short time later carrying a full backpack, but the officers said he didn't enter the apartment.