The CBI is planning to conduct a narco analysis test on Sanjay Roy who was arrested in connection with the alleged rape and murder of a doctor in R G Kar Medical College and Hospital, an officer said on Friday.

The central probe agency has appealed to the city-based Sealdah court seeking permission to conduct the test on Roy, he said.

"This is primarily to cross-check whether Roy is telling the truth. The narco analysis test will help us to verify his version," the officer told PTI.

During a narco analysis test, a drug sodium pentothal is injected into the body of the subject which takes him to a hypnotic state, and his imagination is neutralised, the CBI officer explained.

"In most cases, the accused gives the true information," he said.

The hearing related to the CBI's appeal is expected sometime this afternoon.

The CBI has already conducted polygraph test on Roy inside the Presidency Correctional Home.

Except for the headline, this story has not been edited by The Telegraph Online staff and has been published from a syndicated feed.