Police have confirmed their investigation into the death of birds of prey in the Ross-shire area is now centred on 19 cases, 14 red kites and five buzzards.
Following analysis of the birds' carcasses, 12 have been confirmed as having digested a poisonous substance (nine red kites and three buzzards). Post mortem examinations and toxicology work continues into all the birds seized.
The birds were located within a two square mile area to the south east of Conon Bridge around Conon Brae, Balvail, Leanaig and Alcaig.
The news comes as police raided a number of Black Isle farms this morning investigating the illegal killings.
Up to 10 police cars and vans pulled up outside the farms and began searching farm houses, outbuildings, barns and bins.
Dressed in their usual uniforms but wearing blue protective gloves, officers started looking into barns and yards around the premises with some inside farm houses.
One resident Michael Campbell saw a farmer and his wife leaving their house about 10am soon after police officers pulled up outside.
"It looked like a full blown raid to me," he told The Inverness Courier.
"They have been everywhere, all over the farms, all over the fields. It was a shock."
A spokesman said: "Police are currently conducting searches in the Conon Brae area as part of ongoing enquiries into a wildlife crime investigation regarding the death of 17 birds of prey consising of 13 red kites and four buzzards.
"Landowners in the area are cooperating with the searches."
The move comes as the reward for information following the deaths rises.
A group of farmers and landowners from the Moray Firth have come together and pledged a reward of £12,000 for information about the deaths of the 17 birds of prey in the Highlands.
It brings the reward total to £25,000.
One of the landowners involved in collating the reward is Alex Matheson from the Brahan Estate, which operates the Tollie Red Kites centre in partnership with RSPB.
“We have been appalled by these tragic and senseless bird deaths," he said.
"By pulling together as a community to do all we can to help, we want to send a strong and clear message that any form of wildlife crime is totally unacceptable. We would urge anyone who has any information to come forward.
“Scottish Land & Estates and NFU Scotland have both fully supported this initiative. We call on all sections of our local communities to work with the police - and through appropriate organisations such as PAW Scotland - to create effective partnerships in order that we can totally eradicate all incidents of wildlife crime.”
The reward will be paid for information that leads to the successful prosecution of the perpetrators of this crime. Any information on the deaths should be given directly to the police by calling 101. If anyone would like to contribute to this reward they should contact Brahan Estate directly via email email@example.com
People are being warned that if they find any further dead birds or animals in the area to make a note of its location and inform the police on 101. Under no circumstances should anyone touch or attempt to recover any dead animal.
Police are keen to speak to anyone who has any information about the incident and would encourage them to contact Police on 101 or Crimestoppers anonymously on 0800 555 111 or online at http://www.crimestoppers-uk.org/. No personal details are taken, information is not traced or recorded and you will not go to court.