Slowly but surely pieces of the jigsaw puzzle of the conspiracy behind Mumbai terror attacks are falling into place.

In a first in terror strikes in the country, all the 10 terrorists involved in the Mumbai attack got familiar with the terrain of the city by using the Google Earth service, according to sources in the Maharashtra home ministry.

The 10 terrorists left Karachi in a boat around one week back. After arriving on the Indian coast near Porbandar in Gujarat, they raised white flag on their boat and anchored it outside Porbandar.

• Terror strikes at Mumbai's heart

The occupants of a fishing trawler in the area saw the white flag and decided to approach the boat to find out whether the men needed any help.

But as they approached the boat,   two or three terrorists, in the garb of asking for help, entered the trawler and killed three of its four-member crew. Then the terrorists shifted their arms, ammunition and other equipment to the fishing trawler and forced the remaining member of the crew to sail the trawler in Mumbai's direction.

After coming within four nautical miles of Mumbai, they killed the lone crew member and shifted their arms and ammunition to two dingy boats and landed on the coast near Koliwada. The abandoned fishing trawler � Kuber - was subsequently ceased by the Coast Guard.

From the communication intercept made by intelligence agencies during the operation, satellite phone records recovered from Kuber and revelations made by arrested terrorist Mohammed Ajmal Kasam (21), a resident of the Faridkot district in Punjab province of Pakistan, it is clear that these terrorists have a Pakistani connection.

"However, we have to ascertain whether their operation had any sanction from the Pakistani establishment, what was the involvement of the ISI, which group of Islamic militants these terrorists belonged to, and whether underworld don Dawood Ibrahim [Images] financed this attack," the sources said.

They added that for carrying out such an operation, one needed to go for a rigorous commando training of two years. "The skills shown by these terrorists were almost comparable to that of the NSG," a source said, adding, "Such kind of training can only be provided by a body like the ISI."

Kasam, along with Abu Ismaili Khan, was involved in the attack on the CST station, where almost 50 people died. Abu got killed in the encounter with the police at Marine Drive [Images].

All the terrorists were in the age group of 19-21 and they were carrying the ID cards showing them as the students of different colleges in various cities across the country.

So far, the police have recovered 10 AK-56 rifles, automatic pistols, unspecified numbers of hand grenades and two bombs with 8 kg of explosives. Besides, Rs 6,200 in Indian currency was recovered from the terrorists.