Bishnoi was arrested by the Rajasthan Police with the help of their Madhya Pradesh counterparts from Nemawar area last night.
The case had grabbed headlines in 2011 after the name of then Rajasthan minister Mahipal Maderna cropped up in connection with the murder of Bhanwari, an auxiliary nurse midwife (ANM).
CBI Spokesperson R K Gaur said in New Delhi today that the agency has got seven days custody of Bishnoi during which she will be questioned on various aspects of the case.
The CBI has so far filed three charge sheets against 17 accused, including Maderna and former Congress MLA Malkhan Singh, in the case.
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Among the accused, 15 are in judicial custody, one is out on bail while Bishnoi was absconding.
Bhanwari, posted as auxiliary nurse midwife at a sub-centre in Jaliwada village, around 120 km from Jodhpur, had gone missing on September 1, 2011. She disappeared after a CD allegedly showing Maderna in compromising position with the 36-year-old nurse was aired by some news channels.
Maderna (65), who then represented the Osian Assembly constituency, was arrested on December 2, 2011 in Jodhpur by the CBI along with Parasram Bishnoi, brother of Malkhan Singh.