A pregnant seal found dead on a river bank had been shot through the heart, an examination has confirmed.
The animal was one of two discovered at Walton-on-the-Naze in Essex on 7 January, sparking anger from conservation groups.
They were sent for dissection and the Zoological Society of London confirmed one of the seals was shot with a rifle.
It said the angle and location of the wound suggested the seal was "supine on a sandbank" when it was shot.
Warning: An image follows which some readers may find distressing.
"The bullet had penetrated part of the heart and the edge of the left lung," it said.
The dissection was carried out by the Cetacean Strandings Investigation Programme (CSIP), part of the Zoological Society of London.
A report by Rob Deaville, CSIP project manager, said the adult seal was "in very good nutritional condition" and pregnant with a two to three-month foetus.
"We found the cause of death to be consistent with shooting, with a single entry wound between the fore flippers," he wrote.
"The bullet was recovered during the examination and appeared to be largely intact."
He added: "Given the location and apparent angle of the entry wound, in my opinion the seal was unlikely to have been shot while in the water and the findings are most consistent with the seal being supine on a sandbank when shot."
Tony Haggis, who has run wildlife boat trips off the coast for 20 years, found the animals when they were washed up in January.
At the time he said he was "angry and disgusted" at what had happened.