Detectives are appealing for help to find a mobile phone belonging to murdered mother-to-be Nikitta Grender.
The heavily pregnant 19-year-old was attacked at her flat in Broadmead Park, Liswerry, Newport, South Wales, on February 5.
She was stabbed twice and her flat set on fire by her killer in a desperate bid to destroy evidence.
Carl Whant, 26, was arrested on suspicion of the murder on Wednesday and continues to be questioned by police.
The former soldier, who worked as a bouncer in Newport, is the second cousin of Miss Grender's boyfriend and father of her baby, Ryan Mayes, 18.
Now Gwent Police are appealing for help in locating Miss Grender's missing Samsung Tocco SF80 mobile phone.
Police also revealed that Thursday's appeal to trace four people captured on CCTV in the Broadmead Park area has been successful. Three of the four potentially vital witnesses have come forward and officers received 36 calls connected with the appeal.
One remaining potential witness, seen walking on Fosse Road, Pontfaen, at 5.59am, has yet to come forward. "That person could well hold vital information. Police would like him to get in touch as he may have seen something relevant to the investigation," a police spokesman said.
Detective Superintendent Geoff Ronayne, who is heading the investigation, said: "Although intensive searches have been carried out over the last few days, we have yet to find Nikitta's mobile phone, a Samsung Tocco SF80. We had a very good response from the appeals we made (on Thursday) and three out of four people captured have already come forward. We are grateful to the local community for their response to the media appeals."
On Thursday night police were granted an extra 36 hours to question the man they are holding.