Zakaria Street: The owner of a jewellery business in this central Calcutta commercial district has been arrested for the murder of gemstone trader Mohammad Salim, who was found dead in his shop on Monday night. Sources said at least one more person allegedly involved in the crime had been identified.

The arrested trader is Mohammad Ashar Firdausi, 32, whose shop named Diamond House is located at 5 Zakaria Street, within 10 metres of Salim's jewellery store.

Firdausi deals in precious stones, just as Salim did. Sources in the locality said he knew the victim well and would often seek his opinion on matters pertaining to their common business.

"We are finding it difficult to believe that another shop owner from the same area killed my brother. We cannot think of any possible enmity my brother had with anyone," said Salim's brother Mohammad Naseem.

Relatives of the victim said Firdausi was at the burial ground during Salim's funeral and also at the mosque where a memorial was organised by his family.

Investigators could not immediately point to a motive behind the crime.

Additional commissioner of police (crime) Vishal Garg said it appeared that Firdausi had possibly committed the murder to steal precious stones from Salim's shop.

But a section of the police said it was unusual for a trader to kill someone involved in the same business just because he was doing well.

"He has had his shop here for over a decade. I have known him for 15 years. But it is difficult to say who meets whom outside the workplace," said another trader who owns a shop on Zakaria Street.

The police suspect that Firdausi, a resident of Bhukailash Road in Ekbalpore, had hired goons to execute his plan, knowing that Zakaria Street would be deserted after 8pm.

They believe that the other accused had posed as businessmen to strike a fake deal with Salim, possibly as an excuse to meet him. Salim, during his last phone call to his wife, had told her that he was expecting a client from Asansol and would be late in returning home.

Sources in the homicide department said investigators cracked the case by analysing the "call dump" from the mobile phone tower closest to Salim's shop. A call dump is a digital compilation of all calls made and received through that telephone tower.