And while in hindsight, Pickton appears to have been the best and only suspect worth looking into, retired Staff Sgt. Don Adam said police needed to investigate every suspect to determine whether they were linked to the disappearances.
Adam led a joint RCMP-Vancouver police task force known as Project Evenhanded, which was formed in January 2001. Within a few months, the list of viable suspects had ballooned into the hundreds, he said.
"This file was full of hideous human beings, and they needed to be looked at," Adam testified Wednesday at the public inquiry into the Pickton case.
"If you think of Mr. Pickton as a bright red ball, you can move that ball anywhere in this room and none of us will miss where it is," he said. "But if you brought in 30 red balls, suddenly it's not so easy. By February, there are 60 of them. When Evenhanded had fully assessed everyone, there are 374 of those balls."
Adam outlined a number of challenges faced by Project Evenhanded investigators between January 2001 and Pickton's arrest in February 2002, including the massive list of suspects, the team's mistaken belief that women were no longer disappearing, and the lack of a centralized DNA databank for missing people.
Project Evenhanded was among three separate but related investigations involving Vancouver police and the RCMP.
Vancouver police were investigating the disappearance of sex workers from the city's Downtown Eastside while the RCMP detachment in Port Coquitlam, where Pickton lived, was looking at Pickton as a suspect.
Project Evenhanded was created to compile cases of missing sex workers, identify potential suspects and search for links using DNA and other evidence.
A long list of suspects who had previously sexually assaulted, abused or murdered sex workers quickly emerged, Adam said.
Tips implicating Pickton surfaced as early as 1998, but Adam said investigators couldn't focus on a single suspect because they were working on the theory that there were several serial killers. That theory turned out to be correct, Adam pointed out, as some women on their list were connected to killers other than Pickton.
Adam also rejected the suggestion that Project Evenhanded was merely a historical review, rather than an active investigation.
"That's just not true," he said.
"Because of the nature of what I needed to do, there definitely needed to be file reviews (of Vancouver police missing persons cases). I immediately realized that initiative needed to co-exist with another initiative, and that is investigation."
Still, Adam conceded his team didn't realize women were still disappearing from the Downtown Eastside for many months after they started their work.
Adam said investigators realized their mistake in August, when a member of the team realized that Patricia Johnson vanished in the spring of that year. Johnson was reported missing in May 2001, but for reasons that Adam couldn't explain, the documents that Project Evenhanded initially relied on incorrectly stated she hadn't been seen since 1994.
Adam said August marked a "watershed moment" that prompted his team to change their focus, but a previous witness suggested it took even longer for Project Evenhanded investigators to realize women were still disappearing.
Deputy Chief Jennifer Evans of the Peel Regional Police, who conducted an external review for the inquiry, noted log entries from investigators as late as mid-October indicated Project Evenhanded had yet to realize women were still disappearing, and she wrote that it wasn't clear when that changed.
Another factor Adam pointed to was the lack of a national DNA databank for missing people, which meant there was no central database to house DNA profiles of the missing women. That left no way to quickly compare DNA profiles if remains were found.
At the time, the only national databases were for convicted offenders and DNA samples collected at crime scenes, so there was no searchable missing persons database.
Adam noted that more than a decade later, nothing has changed.
"I know they (the federal government) has been talking about a missing persons DNA databank since 2000," he said. "It's not for me to get bitter, they simply don't have the legislation.
"I just pray that you can fix that," he added, speaking directly to commissioner Wally Oppal.
In the end, none of the formal investigations into Pickton and the missing women cracked the case.
Pickton was caught essentially by accident in February 2002, when a Port Coquitlam RCMP officer who wasn't on any of those investigations obtained a search warrant on a tip about illegal firearms.
Project Evenhanded investigators tagged along and immediately stumbled upon the remains and belongings of missing sex workers.
The remains or DNA of 33 women were found on his farm, although he was only convicted of six counts of second-degree murder. He claimed to have killed a total of 49 women.