He was brought to the Central prison here for questioning from Kozhikode Medical College Hospital, where he was admitted for treatment.
A lower court had yesterday remanded Jayarajan to CBI custody for three days in connection with the murder of RSS activist Kathiroor Manoj.
CBI had in January listed Jayarajan as 25th accused and framed charges against him under the Unlawful Activities (Prevention) Act in connection with the case.
Manoj (42), a district functionary of RSS, was hacked to death in politically volatile Kathiroor in Kannur district on September 1, 2014, allegedly by a group of CPI(M) workers.