Highly-placed sources in the agency said the first post-mortem was conducted at night, which is usually against laid down procedures. Post-mortem is not conducted after sunset except in emergency cases.
Ahead of exhuming, CBI will constitute a medical board after which the agency will move a local court for a direction for exhuming the bodies of the two girls for a fresh post-mortem.
The move comes after the autopsy report of the state government was only suggestive of rape without conclusively proving it. The post-mortem was conducted by a lady doctor who had no prior experience of it, said the sources.
The two cousins, aged 14 and 15, went missing from their house on the night of May 27 and their bodies were found hanging from a tree in the village in Ushait area the next day. The incident had sparked a nationwide outrage.
Meanwhile, CBI continued the polygraph test of the fathers of the victims at the Central Forensic Science Laboratory. The sources said a number of questions were put to the fathers and eyewitnesses regarding the sequence of events on the night when the girls went missing, mobile phones of the girls, first time when parents came to know about the incident but the answers were not clear.
CBI sources said four persons -- fathers of two victims, a relative of the family and an eye witness -- have been brought for lie-detector tests, as the agency is not convinced with the statements given by them.
The sources said the chain of events given by the eyewitness has many loopholes which need to be clarified before reaching any conclusion. They said the statement also lacks consistency.
The sources said CBI has taken three days’ time from the court in Badaun to subject these four persons to polygraph or lie-detector tests but if the procedure is completed earlier, then they may be allowed to go.
CBI sources said they do not doubt the claims made by the families of the victims but in order to develop a flawless case the agency needs to test the veracity of their statements.
Badaun rape: Family holds dharna under tree where they were hanged
Budaun gang rapes: Victims' families say they are not safe
It's Badaun AGAIN: 3 minors assaulted, gang-raped by 7 men
UP gang rape: 'Hang the accused publicly; don't need compensation'
CBI granted 3 months to furnish details on NGOs