Blood spatter expert testifies about Kristin Johnston's death at murder trial

Kristin Johnston suffered a violent death, as revealed by the blood scattered and pooled at the crime scene — evidence that was detailed Tuesday by a police officer to the Halifax jury at Nicholas Butcher's second-degree murder trial.

Sgt. Adrian Butler, a blood spatter expert, testified in Nova Scotia Supreme Court that the bloodstains on the bed where Johnston was found lying on her back, dead, on March 26, 2016, were consistent with blood from the 10 wounds to her neck.

"Saturation stains and hand transfer stains were located on the bottom half of the pillow," said Butler, as the jury flipped through a book of crime scene photos. "A large, concentrated saturation stain — 60 centimetres by 121 centimetres in size — was located on the north side of the bed."

Under questioning from Butcher's lawyer, Peter Planetta, Butler said he only took a swab from the edge of the pool of blood on the bed, and couldn't rule out another source for some of the blood.

Hundreds of spatter stains

The court has heard evidence that Butcher, 36, killed Johnston, his 32-year-old girlfriend, and cut off his hand with a power saw. He has pleaded not guilty to second-degree murder.

Johnston, a Montreal-born yoga teacher, was found dead at her Purcells Cove-area home.

Butler said he also found "cast-off" bloodstains on the bedroom wall that were consistent with blood being sprayed by the spinning blade of the mitre saw when it came into contact with the blood source, presumably Butcher's right arm. 

Butler told the jury there were pools of blood on the bedroom floor near the mitre saw, hundreds of spatter stains on the wall, transfer stains on the handle of the saw itself, drops of blood leading to the bathroom and bloodstains on the door, stairs and railing leading to the basement.

Medical examiner's testimony

Marnie Wood, a medical examiner and forensic pathologist, told the jury there were sharp-force injuries on Johnston's neck that severed her jugular veins, causing her to die of blood loss.

Johnston would have died within a couple of minutes, though it would have taken about five minutes for all the blood to drain from her body, Wood said.

Although a razor blade was found in the bed, Wood said Johnston's neck wounds were consistent with knife wounds rather than razor blade wounds.

The injuries, Wood said, did not support the idea of suicide as a cause of death, and the case was classified as a homicide.

In response to questions from Planetta, Wood said seven of the 10 neck wounds were cut wounds, which are longer than they are deep, and the other four were stab wounds, which are deeper than they are long.

She testified it appeared there was a short struggle at the scene and that Johnston's hands had what appeared to be defensive injuries, as though she was trying to ward off an attack.

Computer expert testifies

RCMP Cpl. Christian Hochhold, an expert witness in the field of forensic examination of computers and other electronic devices, also testified Tuesday.

He analyzed a Samsung cellphone that belonged to Johnston. Hochhold told the court cellphones contain a "plethora" of information, including emails, text messages, videos, photos and social-media posts. 

A Halifax Regional Police officer testified last week Johnston's head was covered with a pillow and a black-handled steak knife was next to her on the bed.

A forensic DNA expert testified this week that both Johnston's and Butcher's DNA were found on the knife. 

The trial began two weeks ago and is before a judge and jury. The Crown expects to call about 40 witnesses in the case, which is scheduled to run for 20 days.

The CBC's Blair Rhodes blogged from court Wednesday. Those on mobile can read here.