Rare birds of prey found dead in Northumberland were poisoned, police have confirmed.
The bodies of two red kites were sent for tests after they were found by a landowner in Hexham in February.
Post-mortem examinations on the birds by specialist vets in Newcastle revealed they had died after eating carrion laced with poison.
Red kites are a protected species and anyone found guilty of killing them faces a jail term or a heavy fine.
The birds were found close to each other on 12 February and showed no evidence of bullet injuries.
'Barbaric and indiscriminate'
A Northumbria Police spokesman said: "In the past red kites have been persecuted and we need to find out who has done this."
Regional director for Natural England Rob Aubrook said: "Thanks to a re-introduction programme started in 1989 there are more than 700 pairs of red kites in England.
"However, these beautiful birds are still vulnerable to illegal persecution and poisoning."
James Leonard, investigations officer at the RSPB, added: "This type of poisoning is both barbaric and indiscriminate.
"Not only does it pose a risk to birds of prey, but also to other wildlife, domestic animals and users of the countryside."