SAINT JOHN, N.B. -- Richard Oland's final moments as he was bludgeoned to death in his office are being traced in court through the patterns of bloodstains and spatter that radiated around his body.

RCMP Sgt. Brian Wentzell, a forensic bloodstain expert, is taking the murder trial of Oland's son, Dennis, through a detailed analysis of the trajectory of blood as the multimillionaire businessman was killed by repeated blows.

Wentzell said Thursday blood "radiated in all directions," with some spatter landing more than three metres from the body.

He said Richard Oland's office desk, where it appears he was sitting when the attack began, had "in excess of 100" stains on it.

A few bloodstains, especially on one side of Oland's desk, indicate that his head was at a low level at some point during the attack, meaning he was likely on the floor as the blows continued.

He was hit over 40 times in an attack with a sharp-edged and blunt, hammer-like weapon or weapons that cracked his skull in several places. Deep cuts on his hands suggest he tried to protect himself from his attacker.

No weapon was ever found.

Wentzell's examination of the victim's clothes also found "biological material" on his blue sweater and in nearby blood spatter -- another indication of the ferocity of the attack.

Richard Oland's body was found on July 7, 2011, lying by his desk in his uptown Saint John office. The 69-year-old former Moosehead Breweries executive was killed sometime during the evening or night of July 6, 2011.

His only son, Dennis, 51, is the last known person to have seen his father alive. He was charged with second-degree murder in 2013. He was convicted by a jury in 2015 but the verdict was set aside on appeal in 2016 and the new trial ordered.

The current retrial is expected to last until mid-March.

Wentzell was not called in by Saint John police until July 10, 2011, and he arrived from Halifax on July 11. By that time, the body had been removed, a few things had been shifted around and there had been considerable traffic in and out of the crime scene.

He said he was unable to specify the origins of several transfer bloodstains in the Oland office, including a couple located on the floor. Wentzell told the court he could not detect any pattern in the transfer stains that would clearly identify them as coming from footwear. He also found transfers on the back of Oland's office chair.

Wentzell noted that some of the bloodstains radiating around the office appear to be from cast-off blood, possibly from the weapon as it was repeatedly raised and lowered.

Wentzell's testimony is important to the defence team, which is expected to cross-examine the bloodstain expert on Friday. During the first trial in 2015, defence lawyers used Wentzell's analysis to question how someone could carry out such a violent attack and not be covered in blood.

Very little blood was traced to Dennis Oland despite an extensive police search of the car he was driving when he visited his father on the day of the murder and items he was carrying at the time.

Wentzell told the court he examined several articles of clothing seized by Saint John police from Dennis Oland's home a few days after the murder. The court has been told in opening prosecution statements that the only confirmed bloodstains were found on the brown sports jacket Oland was wearing on July 6, 2011.

Photos of the jacket shown in court Thursday indicate stains on several locations of the jacket, including on the outside and inside of the sleeves. Because of the dark colour and twill pattern of the Hugo Boss jacket, it is difficult to see the stains on the outside of the jacket with the naked eye.

The jacket was dry cleaned in the days following the July 6, 2011, murder.

In his interview with police on the day his father's body was found, Dennis Oland said he was wearing a navy jacket. But eyewitnesses and security video made it clear he was wearing the brown jacket. His defence team has insisted it was an honest mistake.

The stains on the brown jacket were subsequently found to match the DNA profile of his father.