The dolphin was removed by environmental health officers
Mystery surrounds the discovery of a dead dolphin in the garden of two sailors in Dorset who live on a steep hill half a mile (0.8km) from the sea.
Mike Elliott, 28, and housemate Gary Harvey, woke to find the 3ft (0.9m) dolphin in Portland on Thursday.
The mammal appeared to have two puncture wounds in its stomach as if it had been speared.
Police carried out house-to-house inquiries but said there was no evidence a crime had been committed.
Mr Harvey, 23, said: "I woke up, looked out of my window and saw what appeared to be a dolphin in the garden.
'No tidal wave'
"I went downstairs to have a closer look and that confirmed it - there was a three foot dolphin in the back garden.
"I really don't know how it got there. I was pretty amazed. I thought I was dreaming to start with.
"There was no tidal wave and we live about half a mile from the sea quite a bit above sea level at the top of Portland so it must have been dumped there."
The two men, both Royal Navy marine engineers, called police who made enquiries about the dolphin.
"There was no evidence a criminal offence had been committed," a Dorset Police spokesman added.
Environmental health officers from Weymouth and Portland Borough Council were contacted and removed the mammal, which died of unknown causes.