Looking for clues to Wednesday's serial blasts, Maharashtra's Anti-Terrorism Squad has fanned out teams to various locations across the country and prepared a sketch of the suspect based on eyewitness accounts.

In a related development, Fayaz Usmani, brother of 2008 Gujarat blast suspect, Afzal Usmani, died in hospital after being questioned by police in connection with the blasts in Mumbai.

His family has alleged that he was tortured in custody.

Meanwhile, a senior ATS official said the sketch of a suspect in the serial blasts that left 19 dead and injured over 130 has been prepared.

"The sketch of the suspect is ready. It will be circulated among the select and top investigating officials. It will not be released to the public," said the ATS official.

The sketch will also be shown to the select police informers to get identification of the suspect, the official said refusing to divulge any further details.

The sketch was prepared based on an eyewitness account at one of the three blast sites, the official said.

ATS chief Rakesh Maria said: "We are in touch with UP, Gujarat, Delhi, West Bengal, Andhra Pradesh and Karnataka police, as well as all the central agencies. It is an all out effort."

"Our teams have fanned out to various locations. People in various modules who have been arrested in the past, they are being questioned to help us in this investigation," he said.

Brijlal, Special DG, Law and order, UP police said, "Whenever a tragedy of this magnitude hits, we try and keep in touch with each other. We are coordinating with the ATS and our team is already there".

Police said Fayaz Usmani, a resident of suburban Govandi, who was picked up for questioning yesterday, died in a hospital in the wee hours today.

Dr Ryan Kumar, a doctor at the hospital said: "He died due to brain haemorrhage. This condition is usually when a person is exposed to some kind of shock".

Doctors said he had no external injuries on his body. Azeem Usmani, the victim's son alleged: "My father was picked up for questioning and pressurised during interrogation. They are to blame for his death."

The Mumbai Police have denied the charge.

Mumbai Police Spokesperson Nisar Tamboli said: "He was brought for questioning by the Chembur unit. He was suffering from hypertension and had not taken medicines for the last three-four days. He was admitted to the hospital last evening and the allegations of torture by police are absolutely untrue."

Tamboli said the postmortem will ascertain the exact cause of Usmani's death. Usmani's wife Rubaida said: "When the police came to take him, they said that they will just interrogate him. He had gone alone. So we don't know what the police questioned him about. I don't know to what extent he was tortured, that he got so tensed. They came back in an hour saying he was unwell, he had vomited and was admitted to Sion Hospital."

SP leader Abu Azmi, who visited the hospital, said: "I will meet the home minister and the chief minister tomorrow.

An inquiry should be conducted. While we all want that the accused should be arrested and hanged, but the police cannot harass a common man to such an extent that he burst a vein in his head because of all the tension".