According to the rules, the CBI re-registers an FIR which is registered by the state police keeping content and accused same.
The agency can, however, differ in conclusion with the state police in its final report.
Tiwari, a 2007-batch IAS officer of Karnataka cadre, was found dead on May 17, his birthday, under mysterious circumstances near a guest house, where he was staying, in the high-security Hazratganj area of Lucknow.
He was posted as commissioner in the department of food, civil supplies and consumer affairs in Bengaluru.
36-year-old Tiwari's family had alleged foul play.
"My son was very honest. Corrupt officers did not like him. They must have somehow got him murdered," Tiwari's father B N Tiwari had alleged in Bahraich, his native place.
Post-mortem report had indicated that Tiwari had died of asphyxia but police had said that an SIT team probing the case was awaiting the test reports of his viscera, blood samples and heart to find the exact cause of the death.
The agency has taken over the case by re-registering the case of murder against unidentified persons.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)