Justice was not fully served with the second-degree murder conviction of Robert William Pickton because the B.C. pig farmer should have been found guilty of first-degree murder instead, says the former lead investigator into Vancouver's missing women.

Retired RCMP inspector Don Adam said rigid court rules excluded evidence that would have convicted Pickton of six counts of first-degree murder in the deaths of six women, meaning the killings would have been deliberate and planned. Under the Criminal Code of Canada, murder is first degree when it is planned and deliberate.

Instead, Pickton, of Port Coquitlam, B.C., was found guilty on six counts of second-degree murder in the deaths of six women who disappeared from Vancouver's Downtown Eastside.

"To me, full justice wasn't done," said Adam, speaking outside the courtroom where Pickton was convicted on Sunday.

Many of the relatives of those killed were also upset with the verdict, saying they thought Pickton should have been convicted of first-degree murder.

Adam was the head of the missing women's task force at the time of Pickton's arrest, and spent hours face-to-face with the now-convicted serial killer.

Don Adam, former head of the missing women's task force, says Robert William Pickton should have been convicted of first-degree murder.
(CBC)

He said jurors should have been allowed to see all the evidence that police turned up against Pickton.

"I believe we've let them down. We took a year out of their lives, we didn't give them everything and then they did what they could," said Adam, who retired from the RCMP last week.

"But I think, what's going to happen when they actually find out everything? How are they going to feel and haven't we betrayed them?"

Adam was referring to a series of rulings made by Justice James Williams about what evidence was admissible and what evidence wasn't.

B.C. Attorney General Wally Opal said that often, police feel optimistic about the evidence they gather.

"And they think all of it should be admissible. And sometimes it is, and sometimes it isn't," he told CBC News.

A sweeping publication ban continues to prevent reporting on any evidence the jury didn't hear — a precaution to protect a possible second trial for Pickton on 20 additional murder counts.

Victim impact statements to be heard Tuesday

Pickton will be sentenced Tuesday in B.C. Supreme Court in New Westminster.

The six second-degree murder convictions of the 58-year-old will automatically result in six life sentences, to be served concurrently.

The court will also hear victim impact statements from the families on Tuesday before Williams rules on parole eligibility.

Pickton could be eligible to apply for parole in as little as ten years, or in as many as 25 years.

But Oppal told CBC News on Sunday that no matter what the judge decides, it will be very unlikely Pickton could convince a parole board to release him.

With files from the Canadian Press