GWENT Police revealed 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.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article