Bhagyadhar Mandal, one of those allegedly involved in killing the deer has been arrested from Khamarasahi village from Kendrapara district, they said.
Akshya Kumar Nayak, forest range officer of the national park, said houses of the suspected offenders were raided and the seizures were made following specific information that poachers had hunted down a spotted deer in the mangrove forest areas within the park.
A case has been registered under sections of Wildlife Protection Act, 1972.
The gang had actively indulged in wildlife poaching activity in the recent past and were adept in the poaching of wild boar and deer, the forest officials said.