Nicole Tamang was being held at a CID camp near Siliguri after being remanded to two week police custody by a Darjeeling court.
Nicole Tamang"s mobile was found from the murder site. Nikal is the member of the Central Committee of Gorka Janmukti Morcha (GJM).
The FIRs had been registered against 23 people including the GJM President Bimal Gurung.
The GJM president also had been accused of involvement in Madan Tamang's killing.
Gorkha leader Madan Tamang, president of the Akhil Bharatiya Gorkha League, was stabbed to death in Darjeeling on May 21, 2010.