It was an apparently routine police call that got Sergeant Michael Walters to search Lisa Posluns's Yorkville office building in the early hours of Sunday, Nov. 3, 2002.

Ms. Posluns's sister, Helen, had dialled the police non-emergency number when her calls to Ms. Posluns's cellphone went unanswered.

It was just before 3 a.m. and the building was locked, but Sgt. Walters knew the heavy front doors would give way if he pulled hard enough.

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While his partner stayed with Ms. Posluns's sister and brother-in-law, Sgt. Walters went methodically from floor to floor, trying each door along the way. Every one was locked, with the exception of Ms. Posluns's office on the fifth floor and a small janitor's closet across the hall.

But when he reached the bottom of the building's second stairwell, Sgt. Walters found a large pool of blood on the floor, splattered blood on the wall, and drag marks that continued under an equipment room door.

Ms. Posluns's mother, who was sitting in court, covered her eyes and wept as she listened to the sergeant's testimony.

The equipment room was locked, but Sgt. Walters said he got a ring of keys from the building security guard.

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With the third key he tried, he pushed open the door to reveal the dark, dingy room where Lisa Posluns's body lay slumped.

"There's a large amount of blood around the body, in the front and her back. She's lying on her left side," Sgt. Walters told the jury. "I could see part of her face. I could see one of her eyes. It was open, staring."

Photos of the scene show Ms. Posluns, a petite 38-year-old real estate agent, wearing black boots, blue jeans and a black sweater. Her blood-soaked green jacket had been thrown over her upper body.

"I made the assessment that the person was dead at that point," Sgt. Walters said.

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Court was told earlier that Ms. Posluns died of massive blood loss. In its opening statement, the Crown said she was stabbed several times in her chest and back, and her throat was slit.

Nelson DeJesus, 36, a former cleaner in Ms. Posluns's office building, is charged with first-degree murder.

In his cross-examination, defence lawyer Stephen Bernstein suggested to Sgt. Walters several times that his version of events was mistaken, and that he may have inadvertently contaminated the crime scene.

He asked repeatedly if the footprints in blood that appear to lead out the exit door from the crime scene were his.

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"You stepped in that blood, didn't you?" Mr. Bernstein said.

"No, I did not," Sgt. Walters replied.

Mr. Bernstein asked if any of the police or forensic investigators had subsequently asked to see Sgt. Walter's shoes, to compare them with the footprints at the scene. He said they had not.

The trial continues next week.