“The night before his death, my father tried to contact the manager four times, but his calls went unanswered. Perhaps he saw something suspicious in some file.

"I am sure there was some business motive to the murder, as in the case of Satyendra Dubey.

"The police should look at the bills and other contract-related documents before and after my father's murder,” said Suraj, alleging the involvement of his father's colleagues.

Thomas, a Kerala State Public Works Department engineer who retired in 1998, had joined ICT about 18 months ago.

On December 11, his family in Muvattupuzha, in Ernakulam district, Kerala, received a call saying that he had been found unconscious in his apartment.

The family members were told that Thomas was suspected to have suffered a cardiac arrest, and that he had complained of chest pain when he left office the previous day.

They were told that Thomas's driver had called him in the morning as usual, but did not receive any answer.

According to phone records, the driver made the first call at 8:41 am, and then at 10:36 am. The phone records showed two more calls from two different numbers.

Some office staff then broke into Thomas's flat, and reportedly found him unconscious. He was taken to hospital, where he was declared brought dead.

But the accident register (4568082) at the Coimbatore Medical College Hospital recorded that Thomas was brought in at 12:45 pm by Anil John, the project manager, who reportedly informed the hospital authorities that he was found hanging.

The doctors noted that there was a ligature mark on his neck and his tongue was protruding, indicating a case of strangulation.

A case was registered (1610/12) at the B-4 Race Course Police Station, Coimbatore, under Section 174 of CrPC (suicide or suspicious death).

Last week, the autopsy report confirmed that Thomas had been murdered.

“The main door of the flat has a self-locking system if the button on the knob is pressed on exit. The inside latch was not locked.

"This means whoever murdered my father came in with his permission and also knew how the lock system worked. It is a clear indication that someone known to my father is involved in the crime,” said Suraj.

“We are following some leads. The SIT is interrogating everyone who was in touch with Thomas or dealt with the project.

"However, as of now there is nothing to show that the manager or others suspected by the relatives would benefit from the murder. So far, we have not been able to establish a motive,” said Inspector T H Ganesan, who is heading the special team probing the case.

Thomas's family members have alleged that his colleagues tried to avoid a post-mortem examination.

But Coimbatore city police commissioner A K Viswanathan said it was the relatives who initially tried to avoid an autopsy. “But we insisted on conducting the examination as is mandatory under the law,” he said.

“We have questioned his fellow workers several times but nothing concrete has emerged. We have no substantial evidence at the moment, but are not ruling out anything,” said Viswanathan.

“Nothing has come to our knowledge about any kind of irregularity in the project, there is nothing on record. ICT has limited role in the project... we only monitor the quality of work done — no agreement, no bills or any payment,” said Suresh Kumar Puri, one of the presidents of the consultant company under which the ICT staff at Coimbatore function.

Ganesh Kumar, a senior NHAI engineer who has been deputed to oversee the project, said in such BOT projects, the money comes from the contractor and not from the government.

“The investigation team contacted me seeking details about the functioning of such projects,” he said, adding that he has not found anything to indicate professional reasons behind the death.

“I know nothing can bring back my father, but I want to make sure that the culprits are brought to justice. I will fight to the end to see that happen,” said Suraj.