The Institute of Conservation of Nature and Forests (ICNF) ruled out on Monday the Iberian Lynx as a possible suspect in the killing of 100 sheep in the last 15 days in Tomar, some 140 km Northeast of Portuguese capital Lisbon.
The possibility of an Iberian Lynx became suspect after experts of the ICNF found a Lynx on the A23 motorway, prompting an investigation.
The report by the INCF concludes that although experts have ruled out the Iberian Lynx as a possible suspect, the cause of the slaying remains a mystery.
"The observable and resulting consequences of the attack show widespread injuries and multiple fractures, particularly of the skull bones, possibly caused by a dog or other large animal,"according to the ICNF report.
Consequently, parish Council President Luis Antunes said he does not believe that a dog could be capable of this, siting a dog's inability to scale a fence protecting the sheep.
Antunes also disregarded the possibility of wolves as a possible perpetrator.
The explanation has caused even more concerns amongst its residents as fears that it could be something bigger arise.
Many of the attacks were around houses in the parish of Paialvo, according to Antunes, saying "This has made many people to be afraid of walking in the streets at night."
"There's the concern that it could be a ferocious animal that was being kept by someone and which has now escaped," said Antunes.
ICNF experts will once again move to the site this week keeping a close monitor and continuous assessment of the situation to definitively identify the animal or animals involved.