Dorset Police is to review its probe into the death of a white-tailed eagle found with poison in its system.
Part of an ongoing conservation project on the Isle of Wight, it was one of three found dead this year.
Tests revealed high levels of the poison brodifacoum, a rat poison, in the bird in North Dorset in January.
The force stopped an investigation into its death in March after it was unable to to confirm deliberate intent to kill the eagle.
Dorset Police said a senior detective has now been asked to review the case.
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Deputy Chief Constable Sam de Reya, from the force said: "As you can imagine detecting the deliberate poisoning of a bird of prey is extremely difficult without local intelligence and information to support the investigation.
"To provide reassurance, a senior detective has been asked to review the investigation and will consider the evidence and liaise with stakeholders, including the Wildlife Incident Investigation Scheme and the CPS."
Tests were carried out on the bird but police said experts were unable to establish whether it was a deliberate act or due to the eagle eating prey containing the poison.
The force has also urged anyone with new information to come forward.
The decision to end the investigation was previously described as "baffling" and "premature" by the RSPB.
The birds are all fitted with GPS tracking devices, allowing their flight paths to be monitored.
The project, run by Forestry England and the Roy Dennis Wildlife Foundation started in 2019 and sees at least six birds released annually on the Isle of Wight.