Thugs set a dog on a pregnant deer and filmed the defenceless animal being savaged and killed on mobile phones, police said today.
The attack took place the front gates of Garth prison in Leyland, Lancashire, when a blue Citroen Berlingo car pulled up and the lurcher was released from the vehicle.
A Lancashire police spokeswoman said: "Witnesses to the incident say the occupants filmed the attack on their mobile phones before driving off and leaving the lurcher feeding on the animal's carcass.
"The dog was captured by police and is now subject to examination and held as evidence."
Lancashire Constabulary wildlife officer Duncan Thomas said: "This is a sickening attack on a defenceless animal and these people must be caught.
"The fallow doe was pregnant. They carried out this crime purely for sport and self-gratification and I would urge anyone with any information about this incident to come forward."
The incident took place at about 4.30pm on Thursday.
Anybody with information should contact Lancashire police on 08451 253545 or Crimestoppers anonymously on 0800 555111.