SAINT JOHN, N.B. -- The lead investigator into the murder of Richard Oland says police suspect a drywall hammer or similar instrument was used to kill the Saint John businessman.

The Court of Queen's Bench has heard that Oland was struck more than 40 times in the head and neck with a hammer-type instrument and a blade-like weapon, but Const. Stephen Davidson told the jury Thursday that while the weapon hasn't been found there has been speculation about it.

"There was speculation a drywall hammer or drywall type of instrument was used," he said.

Davidson said police became aware that was the probable type of weapon early in the investigation after the autopsy.

He was testifying at the second-degree murder trial of the victim's son, Dennis Oland, who has pleaded not guilty.

Richard Oland, 69, was found face down in a pool of blood in his Canterbury Street office on July 7, 2011.

During questioning by Crown Prosecutor P.J. Veniot, Davidson said that aside from the crime scene, police searched the home of Dennis Oland in Rothesay and other areas, such as the Renforth Wharf and nearby Bill McGuire Centre, a multi-purpose meeting and banquet facility.

Davidson said a murder weapon hasn't been found and neither were police able to find an iPhone that belonged to Richard Oland.

Davidson has detailed tests that were done with another iPhone, which was used to call a specific telephone at the Saint John police department to determine the cell towers it linked with. Those calls were made from various locations in Saint John, near Dennis Oland's home and from the proximity of different businesses in Rothesay.

On Wednesday, the court was shown video of the police interview with Oland on July 7, 2011, the day his father's body was found.

During the interview, Oland said he had no involvement in his father's death.

The two had met at Richard Oland's office on July 6, 2011, but Dennis Oland told police that he left around 6:30 p.m. and went straight home except for a quick stop at the Renforth Wharf and beach to see if his children were there swimming. They were not, he wrote in a hand-written statement to police on July 7, 2011.

Oland wrote that he and his wife Lisa later went out to buy cold medication and food at Cochran's Market. The court has been shown security video of the stop at Cochran's.

He said they went home to watch a movie and at one point he went to an Irving station to buy milk.

The trial was scheduled to continue on Friday.