A 21-year-old man has been arrested on suspicion of the murder of a mother and daughter.
Raneem Oudeh, 22, and Khaola Saleem, 49, were found stabbed to death outside their home in Solihull on Monday.
West Midlands Police said it arrested the man in the Sparkhill area of Birmingham at about 22:00 BST on Thursday.
Ms Oudeh's ex-partner Janbaz Tarin had been named as a suspect in the investigation.
Officers launched a murder inquiry after the women's bodies were found in Northdown Road in the early hours of Monday morning.
The force put out several appeals, and independent charity Crimestoppers offered a £5,000 reward for information leading to an arrest.
Computer equipment, mobile phones and a van were seized during raids at addresses in Birmingham and detectives said a suspected murder weapon had also been recovered.
Det Insp Caroline Corfield thanked the community for its support and said: "The response to our appeals has been excellent and tonight resulted in this arrest."
Ms Oudeh and Mrs Saleem, who had five other children, were born in Syria.
Police said their relatives had been informed of the arrest.
West Midlands Police has referred itself to the Independent Office for Police Conduct as it had previous contact with the victims' family.