Police are still searching for the murder weapon, believed to be a knife, used to kill a pregnant teenager in Newport.
Miss Grender was due to give birth to a daughter in a fortnight.
Officers investigating her murder, which has been described as “particularly callous”, say the answer lies in the community.
Police and fire crews were called to a smoke-filled flat in Broadmead Park, Newport, at around 08:00 GMT on Saturday.
The teenager’s body was found in the bedroom of the first-floor flat by crews using breathing apparatus and thermal imaging cameras. Her pet dog, a pug cross, also died in the fire.
Detective Superintendent Geoff Ronayne of Gwent Police said the force believed the crime was “locally based”
“Someone must know who did this and we are urging members of the community to come forward and help us with this inquiry,” he said
“We are working on the basis that this crime is locally based.”
Police have established that Ms Grender had been out with friends on Friday evening and visited a McDonald’s in the Spytty area of the city.
They have appealed for anyone who may have seen her from 1900 GMT on Friday to get in touch.
The crime has been described as “horrific” and “particularly callous” by officers investigating the murder.
“Nikitta was two weeks away from giving birth to a baby girl. This is particularly callous and something we very rarely see.
“When Nikitta’s family should have been looking forward to the birth of her baby they are now absolutely grief stricken.”
Det. Sup Ronayne added: “Someone will know who is responsible. Please come forward to give us that information that we need.”
Anyone who has any information can call the police inquiry team on 01443 865562 or call police on 01633 838111 or the independent charity Crimestoppers anonymously on 0800 555111.