The lone police officer assigned to investigate missing persons while women were disappearing from Vancouver's Downtown Eastside released a torrent of tears and frustration at the inquiry into the Robert Pickton case Tuesday.

Det. Const. Lori Shenher has told the inquiry she was almost alone in investigating the disappearances, that her superiors discounted her growing suspicion a serial killer was responsible and ignored her suggestions it might be Pickton.

She said when she learned officers were scouring the Pickton's suburban pig farm, she wanted it to be anyone but him.

"If it had been someone really tricky or skilled, I could have handled that, but ... it was this person that was so in my sights the whole time."

It left her stunned, she added.

As the outcome from the search became clear, Shenher testified she was left grief-stricken.

"Every time someone's DNA was found on that farm, I was right back there. I was counting, I was counting women, how many women went missing from August, September '99, from that time when I really felt we were really closing in on him."

She told the inquiry that when officers finally came around to believing the disappearances were the work of a serial killer, the complaints of women gone missing stopped.

She said officers theorized the serial killer had stopped, perhaps because he was in jail, had died, or had changed his tactics.

But the disappearances hadn't ended.

Shenher later learned that 13 women had disappeared between 1999 and when Pickton was arrested in 2002. The DNA from 11 of those women was found on the farm.

"We mistakenly relied on that information because reports either weren't taken or misplaced. I'm really not sure what happened."

The inquiry has heard from victims' families that a civilian clerk at the force rebuffed their attempts to file missing persons complaints.

Shenher said shortly before she left the missing persons' review team, she and other investigators were surprised to learn that Pickton had been ruled out as a suspect without explanation.

"I think frustration hung in the air over everything we did that whole fall. We thought we had reached a crescendo, we were going forward we had momentum and then .. it felt like it died," she said of the police investigation in late 1999.

She testified that all the information surrounding Pickton was by far the most compelling of any other person of interest.

Pickton was arrested in 2002 and charged with killing 26 women, but was later convicted of killing six.

Months after he was ruled out as a suspect, Vancouver police moved to wrap up the investigation.

Shenher said her first thought was: "Why? Didn't we find everybody?"

"I didn't understand how we could be winding down."

She felt at the time that much more could have been done to investigate Pickton, to at least rule him in as a suspect or rule him out as the killer, she said.

Shenher wept as she described the impact of the case on her life. She said she left the missing person's review team burned out and disillusioned with police work.

"I just want to be clear that whatever impact that this has had on me is very minor compared," she paused as her voice broke, "in comparison to what the families and friends of the missing or murdered women have gone through."

Shenher told the inquiry she was quite secure that she did a "damn good job" with what she had to work with, but until Deputy Chief Doug LePard conducted a review of the investigation, that was never acknowledged by the department.

She suggested to Commissioner Wally Oppal that part of his inquiry may want to look at the police culture and why it's very hard to be an "out-of-the-box thinker" inside the department.

Officers either assimilate or leave the culture, she said.

Oppal thanked her for her input.

"You've given us an indication of how much of an impact, on a personal level, this horrific tragedy has had on you. I think it helps understand what happened."