Eight persons were detained on Sunday in connection with the alleged gang-rape of a 71-year-old nun in a convent school in Nadia district.
Nadia Superintendent of Police Arnab Ghosh said the interrogation of the eight persons was on and extensive searches were being conducted across the district.
The Sister Superior of Jesus and Mary's Convent School, who is admitted to Ranaghat Hospital, is said to be stable now, hospital authorities said.
West Bengal Governor K N Tripathi hoped that the culprits would soon be arrested and the public also have a responsibility to help authorities to catch them.
"No one should insult any religious institute like this. I am sure that this government will do its best to catch the culprits", the Governor told reporters on the sidelines of a programme in Kolkata.
Herod Mullick, state working president of the Bangiya Christiya Pariseba, a united state forum of all denominational Christians, said at Gangnapur on Sunday that the motive of the culprits was not that of robbery alone, it was an attack on the minority community.
Strongly condemning the incident, Mullick said attacks against Christians have been increasing in different parts of the state.
He claimed that the nun had sought police protection after she got life threats.
The SP had said on Saturday that a study of the CCTV footage at the convent in Ranaghat subdivision had shown visuals of four persons who were allegedly involved in the crime.
The SP had also announced a reward of Rs 1 lakh would to any individual providing credible information leading to the arrest of the accused.
The nun was allegedly gangraped by dacoits at Gangnapur in the early hours on Saturday after which a CID probe was ordered into the incident. The gang also decamped with Rs 12 lakh.
Chief Minister Mamata Banerjee had on Saturday ordered a CID probe into the incident and promised "swift" and "strongest action" against the culprits.
She had said that religious politics was being practised in the name of "ghar wapsi" and that religious fanaticism is on the rise.