The Central Investigation Bureau (CIB) of Nepal Police held Nange Tamang Lama, 59, at the request of the national park officials.
Police confirmed the arrest of Lama, a permanent resident of Mugu district, currently living at Bouddha area in Kathmandu Metropolitan City-6.
Information Officer of the Chitwan National Park, Lokendra Adhikari, said that Lama and 14 others had killed a rhino at Badarjhula post of the park a year ago.
Five persons were already held in connection to the case while others are still at large.
Lama is sent to judicial custody in Bharatpur prison.