The mother and daughter who were stabbed to death at their home in the West Midlands were on the phone to police as the attack unfolded, detectives have said.

A suspect, Janbaz Tarin, is being sought in connection with the killings of Raneem Oudeh, 22, and Khaola Saleem, 49, in Solihull. They were assaulted in the early hours of bank holiday Monday.

Janbaz Tarin, 21, an Afghan national, is being sought in connection with the double murder. Photograph: West Midlands police/EPA

Clarifying “speculation” about police contact with Oudeh leading up to her death, West Midlands police said there had been “a number of calls” from her to police on Sunday night, though they did not specify how many.

They said they were contacting her to try to find out where she was when the “situation quickly escalated”. West Midlands police said the call handler “immediately dispatched officers ... [and] they arrived within minutes”.

Facebook Twitter Pinterest Khaola Saleem. Photograph: West Midlands police/EPA

Police said they had “searched several addresses linked to Tarin, a 21-year-old Afghan national, in Birmingham and seized computer equipment and mobile phones for analysis”. They added: “The suspected murder weapon has also been recovered and a van seized for forensic examination.” The large-scale operation to trace Tarin included a raid on an address in the Sparkhill area of Birmingham.

Officers said a forensic postmortem examination was still being carried out on the bodies of the two women on Tuesday evening as authorities sought to confirm the precise causes of their deaths.

Facebook Twitter Pinterest Raneem Oudeh. Photograph: West Midlands police/PA

The two women died at the scene, police have previously confirmed. They were found by officers shortly after 12.30am on Monday and had both suffered serious stab wounds.

On Monday, their family said they were “devastated with the loss of our loved ones”. A statement read: “We would like to give thanks for all the love and support we have received. We kindly request that our privacy is respected at this difficult time.”

DI Caroline Corfield, who is leading the investigation, said West Midlands police had received a large amount of information from the public, but she called for more on Tuesday evening as officers continued to hunt for the primary suspect.

“This is a shocking, tragic case in which a young mum – who has a two-year-old son – and her mother have both been murdered in cold blood,” she said.

“We need to trace the man responsible … he deserves no protection and anyone who may be shielding him through a sense of misguided loyalty needs to know they are committing an offence and will be prosecuted unless they come forward.

“We have a team of detectives working around the clock to try and trace the killer and get justice for Raneem and Khaola’s family. The response from the public to our appeal has been positive and we are following up all credible lines of inquiry – but we need anyone with information on Tarin’s whereabouts to get in touch.”

The force also appealed directly to Tarin to hand himself in. Dave Thompson, the chief constable, tweeted:

Dave Thompson (@DaveThompsonCC) Huge effort underway to locate this man. Call us, web chat us @WMPolice or tell @CrimestoppersUK if you can help. https://t.co/PFV4vCyvVs

Police asked anyone who saw Tarin not to approach him, but to call 999 immediately.