New Delhi, Oct 4 (IANS): The CBI has conducted narco-analysis and lie-detector tests on the suspects arrested in connection with the gang rape and murder of a schoolgirl in Kotkhai area of Himachal Pradesh's Shimla district, informed sources said on Tuesday.

Central Bureau of Investigation (CBI) sources, however, refused to divulge the tests conducted on particular suspects but said these were conducted last week.

Himachal Police had arrested Ashish Chauhan alias Ashu, 29, driver Rajender Singh alias Raju, 32, Subash Singh Bisht, 42, Deepak alias Deepu, 29, and Lok Jung alias Chotu, 19, for the crime.

The 16-year-old schoolgirl was offered a lift in a vehicle by prime accused Rajinder Singh on July 4 while she was returning home from school in Kotkhai town, nearly 56 km from the state capital.

On the way, the accused and his accomplices raped and murdered her in a nearby forest. Her naked body with injury marks was found two days later.

The case got a new twist after Nepal national Suraj Singh was allegedly strangled by Rajinder Singh in Kotkhai police station lock-up on July 19.

What happened at the police station remained a mystery because the two were housed in adjacent cells with minimal security.

Following the gang rape and murder, Himachal residents held massive protests in the hill state. The victim's family alleged that the "real culprits" belonging to high-profile families had gotten away "scot-free".

Later, on the state government's plea, the Himachal Pradesh High Court recommended a CBI probe. Earlier, the Special Investigation Team of the state police was handling the case.