A contentious DNA analysis that helped snag one of America's most notorious suspected murderers could be used in the hunt for a serial rapist in Vancouver, according to a lawyer who pushed to have it approved south of the border.

DNA evidence has linked a single unknown man to three sex assaults in Vancouver, and police say he could be responsible for five more unsolved cases.

But the genetic evidence taken at the scene of the assaults doesn't match anyone in the national DNA databank, and police have been left to plead with the public for tips. Vancouver police made a public appeal for help on Thursday, but five days later, there are no new leads.

In the U.K. and some parts of the U.S., police would have had one more option before hitting a dead end. That's because laws in those places allow investigators to search for partial matches in the offender DNA databank and identify possible family members of unknown criminals.

"Using familial DNA searching, you can continue to try and solve a case when those other steps have failed," said Rockne Harmon, a retired California deputy district attorney and one of the technique's biggest proponents.

"We do know that crime seems to run in families for complicated reasons."

Privacy advocates have lobbied against allowing the new technique in Canada, arguing that it submits relatives of convicted offenders to unfair genetic surveillance.

But thanks to familial DNA searching, Los Angeles police were able to identify Lonnie Franklin Jr. as a suspect in the brutal "Grim Sleeper" killings -- the murders of at least 10 people over 25 years.

When investigators compared genetic samples taken from the scenes of the Grim Sleeper murders with California's offender DNA database, there were no exact hits, but investigators were able to create a list of about 150 close matches -- potential family members of the vicious murderer.

Analysts then compared the Y sex chromosomes from those 150 people with the Grim Sleeper's, and found a match so close, the offender had to be either the father or the son of the serial killer.

As it turns out, Franklin's son had recently been arrested, and swabbed for DNA. When police followed the elder Franklin to a restaurant, they were able to take a sample from his cup, and found a perfect match for the Grim Sleeper's DNA.

Familial DNA searching is currently not permitted in Canada, and in the U.S., only California and Colorado allow it, although Virginia appears to be on the brink of approval.

Harmon was the driving force behind California's decision to allow the unique searching technique, and he says that Canada should consider it, too.

"Why would you have a law that would keep you from something that can solve crimes?" he told ctvbc.ca. "It'll help make the world a safer place."

Privacy concerns hinder approval in Canada

The Canadian Department of Justice says it isn't ready to approve familial DNA searching, but a spokeswoman told ctvbc.ca that the government is "actively consulting" with provincial governments, police and privacy advocates about the technique.

Vancouver police and the RCMP declined to comment when contacted by ctvbc.ca, but according to a government report, Mounties have lobbied for the right to do familial DNA searches.

In June, a senate committee recommended that more research should be done on the technique before any decision is made.

"The Department of Justice [should] further study the matter to determine how to appropriately craft a provision that would balance the need to protect society, the need to protect privacy rights and the need to preserve the presumption of innocence," the committee suggested.

A Department of Justice official told the committee that "kinship analysis, while undoubtedly a hot topic, is unlikely to result in many matches because it can be highly demanding of police resources."

Despite the extra man hours that might be needed to do familial searches, Denver's district attorney has offered the required software for free to other interested jurisdictions.

Still, the technique isn't getting much support from privacy advocates.

Some of the arguments against familial DNA searching are that it would turn convicts into "genetic informants" against their own relatives, and that it would unfairly target minorities.

Canada's Office of the Privacy Commissioner has indicated that it will not support familial DNA searching in criminal investigations. In a speech last year, Assistant Privacy Commissioner Chantal Bernier said that her office needs to see more evidence that familial DNA searching can actually catch criminals.

"The effectiveness of familial searches is in doubt, its success rate and application is not well understood, even among law enforcement agencies and, therefore, we would not support it," Bernier said.

She added that the privacy office also has concerns about the moral implications of familial searches.

"Are we comfortable with the deliberate targeting of presumed innocent people, whose DNA has never been subject to inclusion in the DNA databank -- a process that includes a judicial decision at the end of trial that leads to a conviction?" Bernier said.

But B.C.'s civil liberties watchdog isn't necessarily rejecting the idea.

While the BC Civil Liberties Association doesn't have an official position on familial DNA searching, Policy Director Micheal Vonn says that any use of the DNA databank should be strictly controlled.

"That level of highly personal info, highly sensitive information, it has to be tightly regulated," she said.

If Canada decides to introduce the technique, Vonn says it should be only used in the most extreme cases -- crimes like rape and murder.

"What we've always said is that where you have privacy information that has a high degree of sensitivity, it has to have an equally high degree of control ... at the point of limiting to very serious cases," she said.

‘It's easy to create a fiction if you don't understand the process'

Harmon dismisses privacy concerns as a misunderstanding of how a familial DNA search works.

"It's a fiction, and it's easy to create a fiction if you don't understand the process," he said.

In California, scientists at the state Department of Justice handle familial DNA searches, not the police. And until a suitable match is made through Y chromosome analysis, all the DNA samples are known only by their file numbers.

Before Franklin was identified as the alleged Grim Sleeper, California police had used familial DNA searching nine times. In each of those cases, the DNA analysis failed to turn up close matches on the Y chromosome. That means that in each of those nine cases, not a single relative of an offender was placed under surveillance or investigated in any way.

"Throughout this whole process, these samples are just numbers -- nobody knows who they are," Harmon said.

In fact, Harmon believes that adding familial DNA searching to the police toolbox could help the wrongly convicted prove their innocence.

"I guarantee you that it can and will be used to exonerate people," he said. "It's just another tool used to derive whatever truth you can from the biological evidence."