"The four were arrested in Ludhiana on April 1 on the basis of inputs by CID. They are Bangladeshis and have no passport or visa. They had links with the gang involved in the gangrape of the nun, but whether they were present there on that day is being investigated," CID sources told PTI here.
The sources said that a CID team had gone to Ludhiana.
CID had earlier arrested two Bangladeshi nationals Mohammed Salim Sheikh alias Salim and Gopal Sarkar from Mumbai and Habra respectively in connection with the March 14 incident.
"These persons had stayed at Sarkar's home for a few days and that's how his wife knows them. She has identified the seven persons by the photographs of the culprits caught on the CCTV recording at the school," the CID had stated.