SAINT JOHN, N.B. -- One of the most baffling aspects of the Richard Oland murder case was the focus of attention at his son's trial on Wednesday: What happened to the multi-millionaire's cell phone, the only thing taken from the crime scene?

Const. Stephen Davidson, lead investigator of the Oland homicide for Saint John police, is on the stand at Dennis Oland's second-degree murder trial, describing the steps he took to track cell phone calls and texts in an effort to see where the missing iPhone went.

"We made test calls in the city of Saint John and in Rothesay," Davidson said under questioning by Crown prosecutor P.J. Veniot.

The phone, which was never found, and its last known route are key pieces of evidence for the prosecution, which is continuing to lay out its case at the Oland retrial in Saint John.

This is the second trial for Dennis Oland after his jury conviction in 2015 was set aside on appeal in 2016. It is proceeding before judge alone in the New Brunswick Court of Queen's Bench.

When the bludgeoned body of 69-year-old Richard Oland was found on July 7, 2011, on the floor of his uptown Saint John office, the only thing missing was his iPhone. He was wearing a valuable watch, the keys to his expensive car were on the floor near the body and cash in the office was untouched - all indications to police that robbery was not a motive.

Dennis Oland, 50, an investment adviser, is the last known person to have seen his father alive. He was in his father's office from about 5:30 p.m. to 6:30 p.m. on July 6, 2011. Most of the time, the two were alone.

Oland told police that when he left the office at around 6:30 p.m., he headed back to his home in nearby Rothesay, with a stop at the local Renforth wharf to see if his children were swimming there.

Police and prosecutors say the missing phone also was on the move at that time. The last communication received by Richard Oland's cell was a text message from his mistress at 6:44 p.m. on July 6, 2011, and it appears to have pinged off a tower in Rothesay, near the wharf.

Davidson told the court he also did tests to establish distance and time to make the drive, for instance, from the Oland office in uptown Saint John to the Renforth wharf in Rothesay.

"It took 12 minutes and 24 seconds to get to the Renforth wharf," he said, adding that traffic and driving conditions could affect driving time on any given day.

Rogers Communications, Richard Oland's service provider, established the iPhone's movements through data records. Prosecutors have already told the court they intend to call a cellular network expert to testify that cell phones typically connect with the closest tower since that provides the strongest signal.

Davidson said he made the test calls on a phone, similar to the one Oland had owned, in March, 2012.

"I stopped at several places as I travelled to Rothesay, including the Renforth wharf," he said, testing to see how the phone worked and which towers were involved.

As recently as February 2018, Davidson was adding to the cell phone evidence. He said that at the request of the cellular network expert, Joseph Sadoun, he took a series of photographs of cell phone towers in the area. Sadoun will testify for the prosecution in the new year.

Davidson also described to the court an extensive police search of Dennis Oland's home and property several days after the murder, including the garage where officers hunted unsuccessfully for a possible weapon.

During the search, police seized the brown jacket Oland was wearing on the day his father was killed. It had been dry cleaned and did not appear to have blood on it, but later testing turned up small blood stains and Richard Oland's DNA profile.

Autopsy results show the multi-millionaire businessman and member of the well-known Maritime beer-brewing family was killed by over 40 blows to his head with both an axe-like and hammer-shaped weapon, possibly something like a two-sided drywall hammer. The weapon was never found.

The trial is expected to last until March.