(Shutterstock)Teresa Robinson, an 11-year-old girl, attended a birthday party on a First Nation reservation in a secluded, fly-in town in Manitoba, Canada. She was never seen alive again. Her body was so mangled that police initially thought she had been mauled by a bear. Soon after, the death was ruled a homicide.

Now, the Royal Canadian Mounted Police are undertaking a massive DNA dragnet, or DNA Sweep—a tool used by police to obtain voluntary DNA samples—in the remote town of 2,700 people that can only be reached by plane.

Law enforcement have asked all males between the ages of 15 to 66 (around 2,000 people) to voluntarily provide DNA samples—likely the largest sweep in Canada’s history, according to an article in the Winnipeg Sun this week. Authorities will not reveal if they obtained DNA evidence from the remains, or how many sample have been collected so far.

But, according to research in the US, DNA sweeps are notoriously unproductive, and even a waste of time and money. In the US, over 18 sweeps have taken place since the early 90s, according to publicly available research from 2004, yet only one criminal suspect was ever identified. This newest DNA sweep seems to be one of the first in many years.

A study from researchers at Penn State estimated each DNA sample costs approximately $400 to test, bringing the total cost of larger sweeps—including the cost of investigating leads, etc.—at upwards of a million dollars.

Toronto lawyer Enzo Rondinelli told the Winnipeg Sun that the benefit might not be identifying the DNA profile of the killer, but finding out who is unwilling to submit to testing.

“It may be narrowing it down to those who say no,” Rondinelli said. “Because police then say, 'Well, hmm, I wonder why the person is saying no.' In the eyes of the police, you may now seem suspicious and may actually now come in the crosshairs of a much more [sic] greater surveillance than you otherwise would have.”

In the US, a sweep in Miami analyzed 2,300 samples in a case of six murdered prostitutes in 1994—one of the largest on record. The serial killer was identified by other means, according to the research. The only case that was solved through a sweep was a sexual assault at a nursing home in Massachusetts and involved the fewest number of DNA samples taken—25.

DNA profiles obtained are only used for investigatory purposes in the specific case, and are destroyed after the investigation has been completed. Law enforcement around the world have used DNA sweeps to find the perpetrators and to rule out possible suspects.

But civil liberty groups, like the ACLU, maintain that such sweeps are a gross invasion of privacy, and infringe on Fourth Amendment rights.