Ali Abubaker and Naomi Mahdere were talented teenagers. He was a hip-hop poet, riffing about inequality and injustice; she was a polished singer, mimicking pop stars such as Beyonce. In 2011, Ms. Mahdere won a talent competition put on by Calgary's Afrikadey Arts & Culture Society. Mr. Abubaker placed second.

Ms. Madhere, now 19, wanted to study biochemistry and become a doctor. Mr. Abubaker, now 22, was studying civil engineering at Mount Royal University.

At some point, a romantic relationship between the two blossomed. Ms. Mahdere, an Eritrean-Christian by heritage, converted to Islam. Those who knew Mr. Abubaker, whose parents hailed from Eritrea and the Philippines, were alarmed by his religious stridency, which began surfacing in his poetry.

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Ms. Mahdere's mother became so concerned about Mr. Abubaker's views on Islam that she called the RCMP's national security team last year. She told investigators she believed her daughter and her boyfriend were going to Syria to fight in the war. The couple applied for new passports in October, 2013, wanting the paperwork rushed. In November, they presented passport officials with one-way tickets to London, England.

That's when the police stepped in. Working with Passport Canada officials, they picked up Mr. Abubaker, Ms. Mahdere and their friend Hamza Omer, on charges of passport fraud, keeping them grounded in Canada and off a flight to London. All three pleaded guilty. Their combined fines will likely total around $3,000 – a small sum considering the Crown prosecutor argued their actions could have brought the integrity of the entire Canadian passport system into disrepute.

The couple – who couldn't be reached through lawyers, listed addresses or family members – have paid their dues, and are still together. But the case remains important: not just because of what the Mounties allege they could prove, but because of what they couldn't.

Without the ability to amass the proof beyond doubt they need to lay more serious charges, officials are increasingly leaning on other measures and investigative partners for help to disrupt "high-risk travellers" from getting on planes.

The threat of homegrown terrorism isn't new, but the manner in which the RCMP zeroed in on this couple represents a fresh gambit in the fight to identify and stop prospective terrorist recruits before they leave Canada. These techniques, which have attracted the ire of civil liberties advocates, are being deployed amid a growing sense of urgency: Officials are warning that more than 100 Canadians are suspected of involvement in terrorism activities around the world.

"Into that fanaticism"

Tunde Dawodu, who works at building a sense of pan-African identity among creative Calgary youth through the annual Afrikadey weeklong festival, met Mr. Abubaker around 2010. And he has known Ms. Mahdere since she was a little girl. Mr. Abubaker, he said, was a talented artist, but his poems increasingly included religious terms like Allahu Akbar – Arabic for God is great.

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Mr. Dawodu worried about the teenager and tried to talk to him about it. "He was just too much into that fanaticism," Mr. Dawodu said in an interview in Afrikadey's basement office in Calgary.

Mr. Abubaker, in the program guide for the 2011 festival, described his poetry with a softer spin. "Speaking and writing about the injustice, that is what inspires me," Mr. Abubaker said.

Ms. Mahdere described the "rush" she felt when singing in front of an audience. "You go on stage and at first you are nervous, but then you start to feel comfortable and you can really feed off the energy the crowd is giving you," she said in her bio.

In the accompanying photo, Ms. Mahdere is wearing a denim vest, short skirt and fringed boots. Her Facebook profile photo, prior to being removed this week, featured a woman in black niqab with only her eyes visible.

The pair is now "married under Islamic sharia," according to court documents.

Mr. Dawodu tells a story that shows how Ms. Mahdere's religious transformation coincides with her romantic relationship.

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Ms. Mahdere phoned him out of the blue last year with an odd request given she had once wanted to tour the world as a pop singer. She wanted her old pictures deleted from the Afrikadey's website. "I don't want my body to be exposed," he recalls her saying.

In the midst of this conversation, an angry man grabbed the phone. "Listen, this is Naomi's husband," the man said, according to Mr. Dawodu. He, too, demanded the photos be removed.

"He was threatening me with violence," Mr. Dawodu said. The husband never identified himself, but Mr. Dawodu recognized the voice as Mr. Abubaker's.

Undermining "the integrity of the Canadian passport system"

The passport fraud case against Mr. Abubaker and Ms. Mahdere began with a phone call to the RCMP's integrated national security team on Oct. 28, 2013. It was her mother.

"Ms. Mahdere's parents were concerned that Mr. Abubaker and Ms. Mahdere planned to go to Syria to fight in the war," prosecutor Steven Johnston told the court.

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The mother's theory was based on her concerns about "Mr. Abubaker's perceived views on Islam." She noticed her daughter's debit card had been used twice on the same day at Passport Canada.

RCMP co-ordinated with Passport Canada. They found that Mr. Abubaker, Ms. Mahdere and their friend Mr. Omer all relied on the same guarantor as they sought to rush their passport applications. The RCMP spoke with the guarantor and determined he did not meet the requirements. He knew neither Ms. Mahdere nor Mr. Omer and had been out of contact with Mr. Abubaker, who pushed him to sign all three applications.

This was enough for police to charge the three with passport fraud. "What Mr. Abubaker and his cohorts did undermines the integrity of the Canadian passport system," Mr. Johnston, the prosecutor, told the court. Such illegal acts could tarnish Canada's reputation to the point that all citizens would "end up on visas to travel to the United States."

Defence lawyers said the three had no intention of going to the Middle East. Instead, they had planned to attend an Islamic conference in London.

Ms. Mahdere addressed the court during her hearing, disputing any notion that she and her husband ever harboured "radical views."

"We follow mainstream Islam, we don't follow any fringe group or any extremes," she said.

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"Disrupting" suspects

Police in Canada often talk of "disrupting" potential terrorism suspects, language that makes civil libertarians nervous. Critics of the RCMP want police to proceed in open courts. They point out Mounties were faulted by separate judicial inquiries, in the 1980s and early 2000s, for unlawful conduct in their fight against terrorism.

"You don't want some committee in some hidden office in Ottawa making these kinds of decisions that would interfere with someone's right to liberty," said Paul Cavalluzzo, a lawyer who acted as commission counsel during the 2004 Maher Arar inquiry.

But the Conservative government is promising Canadians that authorities will get better at preventing terrorism – and the term "high-risk travellers" (HRT) has gained currency, applied to cases in which officials are long on fears but short on evidence. A senior Mountie chairs Canada's HRT "case management committee," where security officials meet every few weeks to discuss who they need to keep off outbound planes.

Superintendent Wade Oldford, the RCMP's top counterterrorism detective, says the committee was "born out of necessity," especially after "the number of individuals brought to our attention leaving the country started to increase significantly as the events in Syria started to unfold."

The police gold standard for any national-security investigation remains arresting, charging and prosecuting suspects in open court on Anti-Terrorist Act offences. But when they can't reach that standard, they turn to other means. Supt. Oldford, in an interview, gave a hypothetical example.

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"If we knew there was an individual discussing planning to leave Canada for Syria and we didn't have enough information to lay a charge," he said, "then is there something from a Passport Canada perspective they could do under their own legislation?"