There is speculation that the former Jharkhand CM may meet BJP leaders, including Union Home Minister Amit Shah, to discuss joining the party, along with four JMM MLAs.
Sandip Ghosh was asked to furnish details of the phone calls he made before and after the incident at the hospital, an officer of the central probe agency said.
In a communication to the state police forces, the home ministry said that the law and order situation of all states should be monitored in view of the protests.