After the arrest of a New York man charged with killing three women believed to be sex workers, advocates are again sounding the alarm that street sex workers are too often the targets of violence.

On Thursday, authorities in New York arrested Rex Heuermann, an architect charged with first-degree murder in connection with the deaths of three women whose remains were found over a decade ago on Long Island. He has pleaded not guilty. Police say they connected him to the women’s remains using DNA evidence detectives matched between his left-over pizza crust and an item linked to one of the women’s remains.

It’s not news that people who engage in sex work, which is illegal in the U.S. except for in Nevada, are routinely victims of violence from potential clients and the public at large, advocates and a former sex worker told USA TODAY.

“It’s pretty much the norm. People from the community really have to watch their back when it comes to, not only people who they serve in their profession, but also people who they come into contact with who they may refuse services to, and then also police,” said Jasmine Tasaki, executive director of We Care Tennessee, an organization working to protect sex workers and transgender people from violence in Memphis.

In New York, an analysis from the Sex Workers Project at the Urban Justice Center found that 80% of a small group of street sex workers who responded to a survey reported experiencing violence or threats of violence while working.

Thursday’s arrest is also a painful reminder that some of the country’s most high-profile serial killers have targeted street sex workers, said the ACLU’s Gillian Branstetter.

“Sex workers are targets for violence, specifically because the people who are targeting them, like this killer in Long Island, know that they are marginalized,” she said. “They know that they are less able to establish safety, that they are put at risk by a society that criminalizes their profession and by extension their existence.”