The regional manager of the National Parks and Wildlife Service in Kerry, Mr Paddy O'Sullivan, has warned about "jumping to the wrong conclusions" in the case of the deaths of over 40 grey seals on an island off Kerry.
There was no evidence of disembowelling, clubbing or the kind of "sadistic" attack on the seals on Beginish Island, as suggested initially, he said.
A number of the pups had died of starvation, others of unattributed causes, and others had been shot, he believed.
There was no evidence "that there was any of kind of sadistic attack on these seals", Mr O'Sullivan said.
Holes thought to be bullet holes had turned out to be made by gulls in a number of cases.
"We are going to investigate this thoroughly and comprehensively. But I want people to stand back and allow the situation to be assessed properly. We didn't find any evidence of seals being clubbed."
However, the Irish Seal Sanctuary said it was standing by its claims of barbaric slaughter, and that the prompt post-mortem results on three animals sent to UCC for analysis had supported their position.
Initial findings, released yesterday, were that one seal had been shot, one had an instrument driven through its eye, and one had been bludgeoned.
The shocking images of bloodied seals have caused widespread revulsion.
However, it has also emerged that gulls and decomposition may have been responsible for much of the bloodied carcasses and ripped-open bellies.
Mr O'Sullivan said seal pups would naturally have fallen prey to sea birds.
Fishermen have been calling for a cull, because of the quantities of fish that seals eat, and the damage they do to nets.
A Cambridge study found that the mammals can consume 7.5 kilos of fish a day to meet energy requirements.
The Irish South and West Fishermen's Organisation (IS&WFO) condemned the reported killing of the seals.
The organisation said it would be "very surprised" if any of its members were involved in the incident.
Ms Pauline Beades of the Irish Seal Sanctuary said it was not attributing the blame to the wider fishing community.
It would continue to work with the authorities and wanted justice for wildlife and for fishermen, she said.
Initial claims by the sanctuary of widespread disembowelling and bludgeoning have been denied also by the gardaí.
According to one expert investigator who visited the scene, but who did not wish to be named, a large number of the seals had no physical injuries. All had their eyes removed by gulls.
The claimed disembowelling of the pups was the result of damage by birds, he said. "Because when the gull pulls at the stomach gut, the whole stomach opens," he said.
Investigations are being led jointly by gardaí and the National Parks and Wildlife Service. Local veterinary surgeons and the Department of the Marine are also involved.
Mr O'Sullivan has appealed for information on the shootings.
Seal pups naturally have a high mortality rate, and in some cases mothers do not return to feed their young.
Mr O'Sullivan said a number of avenues were being explored, including, in some cases, the possibility of a virus.
An empty bullet shell was found on Beginish, it is understood.
It is an offence to hunt seals under the Wildlife Act, 1976.
The Blaskets are one of the main breeding grounds for grey seals, up to 20,000 of which migrate from Scotland annually. No precise figures are available for abundance, and an Irish-Welsh EU Interreg study on the marine mammal four years ago called for a proper island-wide census before any "sustainable management" strategies could be considered.