Mahajan was on a 14 day parole on health grounds which was scheduled to end on Saturday, Dec 12.
He was reportedly taken to Jupiter hospital following complains of fatigue and severe headache on Friday, Dec 11.
Doctors say that his condition is critical and he is presently in life-support system.
50-year old Mahajan was diagnosed with brain haemorrhage and was admitted in ICU.
Pravin Mahajan was sentenced to life imprisonment in Dec 2007 for shooting his brother Pramod Mahajan on April 2006, who succumbed to his injuries after 12 days.