People who work to keep women in the sex trade safe call the arrest of an Ottawa man on first-degree murder charges a relief, but say the streets remain dangerous for prostitutes.

Marc Leduc, 56, appeared in an Ottawa court Thursday morning and he was formally charged in the deaths of Pamela Kosmack, 39, and Leeanne Lawson, 23.

Kosmack was found beaten to death in June 2008 on a bike path near Lincoln Fields transit station in west Ottawa. Lawson was found dead in a parking lot in Ottawa's Lowertown neighbourhood in September 2011.

Shortly after Lawson's death, then police Chief Vern White issued a warning to sex-trade workers, noting a pattern linking recent murders.

Police had told CBC News more than a year ago they believed a suspect who killed multiple sex workers may be linked to the unsolved homicide of Kosmack, but at a news conference Thursday, Ottawa police chief Charles Bordeleau would not link the two cases involving Leduc to any other unsolved homicides.

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Outreach worker Nicole Edwards said sex-trade workers face many dangers. (CBC)

But people who work with Minwaashin Lodge's Sex Trade Out Reach Mobile program — or STORM — say there is relief on the streets after the arrest.

"He's not been convicted... but...just relief. Relief that maybe this is the guy," said outreach worker Nicole Edwards.

5 unsolved homicides linked to sex trade

Outreach workers at Minwaashin Lodge provide food, clothing, transportation, housing and medical referrals, and other essential services to up to twenty women a night.

Shelly Longboat, a STORM worker, said clients live in constant fear of people who prey on sex trade workers.

"It's a scary thing. They don't know if they're gonna be alive the next day, the next hour. Who knows?" said Longboat.

There are still four unsolved murders of sex trade workers in Ottawa and one in Gatineau.