The high court on March 19 had directed the CBI to take up the probe into the Walayar case.
Taking over the investigation into the mysterious death of two minor sisters in Kerala's Walayar in 2017 after allegedly being sexually assaulted, the Central Bureau of Investigation has registered two FIRs in the case.
The action comes on the orders of the Kerala High Court which had directed the agency to take over the probe without any delay.
The eldest girl, 13, was found hanging inside their hut on January 13, 2017 and the younger sister, 9, on March 4.
Walayar police had come to the conclusion that the girls were sexually abused in unnatural way by five persons including a juvenile for nearly one year till they were forced to kill themselves by the accused by tresspassing into their house.
In January, the high court had ordered a retrial in the case, considering a plea challenging order of a special POCSO court in Palakkad, acquitting the five accused for want for evidence.
The high court on March 19 had directed the CBI to take up the probe into the Walayar case.
The high court gave the directive after considering the state government's consent for the CBI probe into the case.
The central agency can take over any investigation in Kerala only with the consent of the state government.
Earlier, the state government had informed the court that it was not averse to a CBI investigation into the case.
The petition seeking the CBI investigation into the case was moved by the victims' mother.