The Central Bureau of Investigation has carried out a lie detector test on a rickshaw-puller arrested in connection with the murder of National Highways Authority of India engineer Satyendra Dubey.

The polygraph test was carried out on Pradeep Kumar, who was arrested late in December 2003, to ascertain the veracity of his version of events.

S K Dubey's Murder: Complete Coverage

It has been alleged that Dubey was murdered after he wrote to the prime minister pointing out irregularities in the implementation of the Golden Quadrilateral Project in Bihar.

The CBI registered a case against unknown persons under 120-B (criminal conspiracy) and 302 (murder) of the Indian Penal Code and under various provision of the Arms Act on December 14 as the murder was seen as a conspiracy of the builder-mafia entrusted with the work on the project in Bihar.

But according to Kumar, Dubey's murder was more or less the result of a roadside robbery gone awry. He claims the IIT-Kanpur graduate was killed when he resisted robbers.

The CBI managed to trace Kumar by tracking the cell phone stolen from Dubey. He has a criminal history of involvement in similar cases of robbery.

What is known so far is that Dubey had called his driver from Varanasi, where he had gone to attend a wedding, on the ill-fated day. On his arrival at Gaya Railway Station, Dubey found that his driver had not turned up to pick him up.

He called the driver again only to be told that there was a starting problem in the vehicle. Dubey then hired a rickshaw.

Some persons reportedly involved in robberies in cahoots with rickshaw pullers are believed to have followed him.

The CBI will ascertain whether there actually was some problem with the vehicle or it was part of a conspiracy, the sources said adding it would also question and carry out lie detector tests on the driver and other members of the NHAI staff attached to Dubey.

A high-level CBI team is camping in Gaya to carry out the investigation.