"Their killers must be found," the women chanted, many dressed in black for mourning, during the second day of protests in the city of Port Harcourt in the oil-producing Niger Delta region.
Eight women have been strangled in hotel rooms in Rivers State in the past two months, police spokesman Nnamdi Omoni said. He said some suspects had been arrested but a manhunt continues to identify the main culprit.
"The state police command has directed all hotels in the state to install CCTV cameras in their hotels," he said.
Activists asserted, however, that up to 20 women have been killed and said the protests will continue until security is restored.
"We the ladies are no longer safe in this state," said one protester, Lucy Okeke. "All we are demanding is greater protection for the women in the society, all the victims of this so-called serial killer."
Women are angry that police might not be taking investigations seriously, and are labelling all victims prostitutes just because the killings took place in hotel rooms, said activist Emem Okon. Her group Kebetkache Women Development & Resource Centre joined the protests, saying there is a need for women to ask questions about who is behind the killings and why.
Olukoya reported from Lagos, Nigeria.
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