Deputy Chief Jennifer Evans of Peel Regional Police, who wrote a report that was critical of both Vancouver police and the RCMP for their failure to catch Pickton, said she visited the former pig farmer in prison last August.
Evans said she wanted to ask Pickton how he was able to evade police for so long, killing sex workers for years until he was essentially caught by accident in 2002.
But during their interview, which lasted roughly 90 minutes at Kent Institution near Agassiz, B.C., Pickton was of little help.
"His answer essentially was, 'Because I never did anything wrong?'" Cameron Ward, a lawyer representing the families of 25 murdered and missing women, asked Evans as he cross-examined her at the inquiry.
"Because he didn't do anything," replied Evans.
"He maintained his innocence?" said Ward.
"Yes, he did," said Evans.
"And did you think he was telling the truth?" asked Ward.
"No, I did not."
Evans said Pickton admitted to picking up women in Vancouver, but denied killing them.
Pickton spent years luring sex workers from Vancouver's Downtown Eastside to his farm in nearby Port Coquitlam, where he butchered them and disposed of their bodies.
He was able to keep killing for years, despite emerging as a top suspect in the disappearance of Vancouver sex workers as early as 1998.
Pickton was convicted of six counts of second-degree murder, but the remains or DNA of 33 women were found on his farm. He once claimed to an undercover police officer in jail that he killed 49 women.
"Did he strike you as someone capable of murdering 49 people by himself, given your police experience?" asked Ward.
"Of doing it by himself? Yes," replied Evans.
Evans said during the interview, Pickton did not express a desire to testify at the public inquiry.
Commission lawyer Art Vertlieb said in an interview that Pickton would not be called as a witness.
"Given the evidence we've heard (from Evans) we're not calling him," Vertlieb said.
In her report, Evans noted she interviewed Pickton, but she didn't reveal the content of their conversation, writing only: "I can tell you that my interview of Robert Pickton did not advance my work for this review and is not referenced further."
The inquiry opened last October and has so far heard from experts on the Vancouver sex trade and from three police officers who reviewed the various investigations of Pickton and missing women in the late 1990s and early 2000s.
There were several separate but related investigations.
The Vancouver police investigated reports of missing sex workers from the city's Downtown Eastside neighbourhood, while the RCMP in Port Coquitlam worked to determine whether Pickton was involved.
The Mounties had previously investigated Pickton for an attack on a sex worker at Pickton's farm in 1997, although prosecutors declined to bring Pickton to trial on a charge of attempted murder.
Eventually, the Vancouver police and the RCMP formed a joint investigation known as Project Evenhanded. That investigation was conducting a historical review of missing women cases to determine whether they were related.
Beginning next week, the inquiry will hear from officers who were involved in those investigations, starting with former Vancouver police detective Kim Rossmo.
Rossmo was a geographic profiler who was among the first officers to warn there may be a serial killer at work, only to be ignored by his superiors.
In the end, none of the investigations into Pickton or missing women solved the case.
He was arrested in 2002, after a junior RCMP officer in Port Coquitlam obtained a search warrant on an unrelated tip about illegal firearms. Members of the missing women investigation went along and immediately found the remains and belongings of Pickton's victims.