Ottawa area sex trade workers gathered on Parliament Hill Saturday to call for a moratorium on police street sweeps amidst concern a serial predator is at large.

The city's police chief issued a heavy warning to sex trade workers on Dec. 9 to be extra vigilant because investigators have reason to believe workers are being targeted.

CTV Ottawa's Karen Soloman spoke to several supporters and former workers who say stopping police sweeps will help.

"Decriminalization-- that would go a huge way towards putting an end to violence that sex workers face," said protester Allison Armstrong.

A spokesperson for sex workers argues aggressive policing and fear of arrest force workers into more secluded and dangerous situations.

Chris Bruckert said workers are moving to alley ways, dressing down and no longer working in pairs in order to avoid arrest.

Support worker Sunny Marriner said "I'm tired of losing more and more of the young women I've cared about since they were kids and just being left with grief."

Saturday also marked the International Day to End Violence Against Sex Workers. The group remembered prostitutes like Leeanne Lawson, a 23-year-old Ottawa woman found murdered in September. Her killer has not been found.

It is unsolved cases like Lawson's which, many say, point to a bigger picture. There are those who argue sex trade work will not stop and that changing the laws to make it safer would be a step in the right direction.

Last year, an Ontario Superior Court judge struck down federal laws around prostitution, saying they contribute to the danger sex trade workers face.

The federal and Ontario governments appealed that ruling in June. A decision is pending.

With a report from CTV Ottawa's Karen Soloman