"The data obtained from the satellite transmitter indicated that the eagle did not move from one spot on a hill high above Glen Esk, for over 15 hours.
"Then, during the night, when eagles do not readily fly, it has inexplicably moved to a new position, hidden under a tree and close to a road. Here, over the next four days, this eagle suffered a lingering death."
Its body was found, lying face down, with its wings folded and was seized as evidence by officers from Grampian Police. The post-mortem examination was carried out at the Scottish Agricultural College laboratory in Aberdeen.
RSPB Scotland director Stuart Housden said: "Whilst efforts to stamp out the illegal poisoning of birds of prey are perhaps beginning to yield results, this dreadful case shows that the persecution of our raptors continues through the use of traps and other means.
"We call upon anyone who can provide further information about this case to contact the wildlife crime officer at either Tayside or Grampian Police without delay."