The intense tactics being used by police investigating the disappearances of 50 women are long overdue, says a former Vancouver inspector who said a serial killer was at work years ago.

Kim Rossmo says police searches of a pig farm in Port Coquitlam, and of storage lockers could turn up valuable evidence about what happened to the women.

"The search of any property associated with the suspects would be absolutely expected," Rossmo said. "Some serial murderers will collect what are called souvenirs or trophies ... and they'll store them or keep them, either for display or for reflecting on the crime."

Police have searched a storage locker rented by Robert William Pickton, 52, and more recently, one rented by Gina Houston, his neighbour and friend.

Pickton was charged last month with murdering Mona Wilson and Sereena Abotsway.

Police have been searching a farm he owns with his brother David since early February for clues to what happened to 50 women, most of them drug addicts and prostitutes, who disappeared from downtown Vancouver's eastside beginning in 1984.

Houston said on the weekend she is a suspect in the case, and expects to be arrested any time.

Police has seized the contents of Houston's storage bin, including furniture, dishes and some children's toys.

Her storage locker in Port Coquitlam was next to one rented by Pickton, which has also been raided by detectives.

Rossmo, who developed a high-tech method of tracking serial killers while a member of the Vancouver force, said three years ago a serial killer could be operating in the city, but officials wouldn't dedicate resources to the investigation.

Now, he says, police need to be thorough in their search for evidence.

"You only have to look at the Paul Bernardo case, where the police investigators overlooked a key piece of evidence that caused tremendous problems later on at trial and that was the videotape," he said. "They did a very thorough search but it still managed to elude them...

"They are looking for evidence that could be potentially be very incriminating and the offender could have gone to great lengths to hide it."

Houston denies any involvement with the missing women, and said it was a coincidence her locker was next to Pickton's.

Pickton has reportedly not co-operated with police and David Pickton says his brother is beginning to crack under the intense interrogation.