Detectives investigating the discovery of a torso in a bin liner on a beach believe other body parts may have been dumped nearby.
The body, without head, arms and legs, was found by a group of foreign students at Southsea, Portsmouth, Hampshire, at 5.30pm on Tuesday.
Police said the torso is that of a man but a post-mortem examination conducted yesterday evening failed to determine a cause of death.
Identifying the victim - who had suffered a "sustained and violent assault" before death - was proving "extremely difficult", Hampshire Police added.
Detective Chief Inspector Dick Pearson, of the Hampshire Constabulary major investigation team, said: "This is a murder inquiry.
"The fact that we are unable to use more conventional methods to identify the victim, such as fingerprints or dental records, is challenging.
"The inquiry is open to the possibility that the murder may have taken place away from the local area.
"We continue to appeal to the community to contact us with any information which could assist us, particularly any suspicious activity or people on the seafront.
"Members of the community who are in the area regularly will know if something or someone is out of place, or notice unusual behaviour. Please report it to us.
"We are also appealing to anyone who notices suspicious packages, possibly wrapped in black bin liners in the area.
"As we have confirmed, at this stage only a torso has been discovered.
"Other body parts or items linked to the murder may have been discarded in the area.
"If you notice a suspicious package that may be linked to this inquiry do not open it, but contact police immediately."
Anyone with information is asked to call Hampshire Police on 101, quoting Operation Nimbus, or Crimestoppers on 0800 555 111.