A man who the Kenyan authorities said had confessed to killing 42 women over the past two years escaped from custody at a police station, a spokeswoman for the national police service said on Tuesday.

The man, Collins Jumaisi Khalusha, and 12 other people, all of them Eritreans, escaped from the Gigiri Police Station, Resila Atieno Onyango, a police spokeswoman, said in a WhatsApp message. The police station is in a neighborhood that also includes the United States Embassy, a United Nations office and other diplomatic missions in the capital, Nairobi.

Mr. Khalusha’s arrest in July came after the discovery of dismembered bodies at an abandoned quarry in Nairobi, and the revelations rattled Kenya, an East African economic powerhouse, during a period of political turmoil.

The discovery intensified the horror and added to the urgency of tense national debates about violence against Kenyan women. A wave of killings, including at least 31 in January, prompted nationwide protests.

Mr. Khalusha confessed to having “lured, killed and disposed” of women, according to a statement in July by Mohamed I. Amin, who heads the Directorate of Criminal Investigations. John Maina Ndegwa, Mr. Khalusha’s lawyer, accused the police of torturing and strangling his client into giving a confession.

One of Mr. Khalusha’s victims was his wife, the police said: He strangled her, then dismembered her body and disposed of it at the quarry, which was used as a dumping site — and was near a police station.

The police did a forensic analysis of a cellphone belonging to one of the victims to identify Mr. Khalusha. They recovered a machete, nylon sacks, industrial rubber gloves, multiple identification cards, women’s underwear and rope from his house, which was about 100 yards from the dump site, the statement read.

This is a developing story.