Nigerian police investigating the murders of at least eight women lured to hotels in the southern city of Port Harcourt said they had arrested a suspect.Five deaths in the last month have sparked fears of "serial killings" targetting suspected sex workers, and a wave of protests by women activists in the city, the capital of oil-rich Rivers State.Officers have arrested a suspect who had made "useful confessions" and they were pursuing other accomplices, Rivers State police commissioner Mustapha Dandaura said in a statement late Tuesday.They suspected the murders were for ritual practices, he added."After the killings, a white cloth material is rolled on the victims' necks or waists. So, there is an element of cultism in all the killings in the hotels that have taken place," Dandaura said."The serial killer normally drugs his victims and thereafter, he strangles them," he added.Although local reports suggested more than 10 women had been killed, Dandaura said they had only eight verifiable cases, with the first of the victims murdered in July.In recent days, women took to the streets of Port Hartcourt in a series of protests calling for better police protection.Outrage at the killings and the police response spilled over on to social media after police told protestors that women should abandon prostitution to avoid being targetted."We must go back to try to educate them (women) and discourage them from going into prostitution because that is how they fall victim to these crimes," deputy commissioner of police, Chuks Enwonwu told demonstrators, according to local reports.Protesters and activists condemned the police response, saying all women were vulnerable to the rising attacks.Prostitution is illegal in Nigeria, and police have enforced restrictions on hotels in the city, forcing hotel owners to install closed-circuit cameras to monitor activity or face closure.