A sex workers' support group has called for an amnesty for prostitutes and clients after three women were found dead and two reported missing.
The bodies of Tania Nicol, left, and Gemma Adams were found
The naked bodies of Gemma Adams, Tania Nicol and a third woman were found near Ipswich over the past eight days.
Police are also looking for prostitutes Annette Nicholls and Paula Clennell.
The English Collective of Prostitutes said sex workers and clients fear being arrested if they come forward. Police promised anonymity and confidentiality.
Nicki Adams, who spoke to a number of sex workers who work in the vicinity where the dead women were discovered, said of the police: "They did not want to call it an amnesty but they said the women's safety was a priority.
"But the women do not feel that is enough. We are pressing for an amnesty to be formalised until the murder investigation is complete.
"A short-term amnesty would mean the women could come forward with information even if they had an outstanding warrant or had breached an Asbo.
"One sex worker I spoke to said 'a killer like this usually has a history of violence - so how many women may have reported him in the past?'"
A spokeswoman for Suffolk Police said: "We are not looking to prosecute anyone. We have promised anonymity and confidentiality for them.
"Our priority is to trace those responsible for this [the murders]."
But Ms Adams added: "The women I spoke to were fed-up; the police were telling women they should take care of themselves.
"Various schemes like zero tolerance, big crackdowns and street sweeps - where police try to clear the streets of prostitutes over a day or several days - force the women to work faster so they don't have the time to check out clients, who are already freaked out by the police presence."
Ms Adams went to claim that the police "did not appear to have learnt the lessons from the Yorkshire ripper".
"Women are being raped and attacked around the country and the police are systematically dismissing such reports - they do not take them seriously."
New Zealand example
The spokeswoman for Suffolk Police added: "Those are long-term issues that we don't think are appropriate at this time."
Ms Adams also called for prostitution to be decriminalised, citing New Zealand as an example.
According to the English Collective of Prostitutes, more than 70% of prostitute women are mothers.
A spokeswoman said: "As poverty, homelessness and debt go up and women's wages go down, more women [especially with Christmas around the corner] are forced into prostitution to support themselves and their families.
"Every woman is some mother's daughter, someone's sister, aunt, beloved friend. Every life is of value."
Police have appealed for clients of the women to come forward
Her comments come as extra voluntary workers are taking to the streets in the town to give safety advice to prostitutes.
Hannah Besley, community safety officer and chairwoman of Ipswich's prostitutes steering group, said more volunteers from health and Christian organisations were patrolling Ipswich's red light district to provide "reassurance" for women.
"We are urging them to try to work with friends or be in groups, to tell people where they are going and who they are going with," she said.
"Obviously this is a very worrying time and I think people are generally very scared.
"These murders have come as a complete shock and our thoughts go out to the girls' friends and families."