Completion of the investigation marks the first time ever that Pakistan has carried out such an exercise on an issue of key interest to India, its arch rival in South Asia.
The Pakistani official, who spoke to CBS News on condition on anonymity, said it was likely that some of the militants already detained in Pakistan, "will be prosecuted on charges that have yet to be spelled out," without elaborating further.
Western diplomats responding to the news said a prosecution of this kind would be the first ever undertaken by Pakistan, which became a sovereign nation upon separation from India - under British colonial rule - in 1947.
The countries' 62 year history has been largely overshadowed by bitterness and anger surrounding the division of the disputed Kashmir region, a mountainous Himalayan state. Nuclear armed India and Pakistan have fought three major wars and numerous skirmishes during this time.
The Mumbai attacks were followed by widespread international anxiety over the possibility that India might launch limited air strikes on suspected militant targets in Pakistan. That move would have inevitably prompted Islamabad to retaliate, a situation which could quickly have triggered an all out war, analysts warned.
Following the siege, Pakistan immediately came under intense pressure from the United States and other allies to take action against militants in the country, at the insistence of India.
Pakistan banned Jamaat-ud-dawa (JUD), an Islamic charity believed to be a front for Lashkar-e-Taiba (LeT), the Islamic militant group believed to have been behind the attacks, which was banned more than six years ago.
Pakistani government officials have complained repeatedly that India has failed to hand over credible evidence that could be used to prosecute the Mumbai suspects.
However, a senior Western diplomat told CBS News Thursday that Pakistan is considering trying some of the suspects under its cyber-crime laws, based on evidence that the Internet and other communications technology were used between the attackers and their backers in Pakistan.
"This is a way to put these people behind bars," said one diplomat, who also spoke to CBS News on condition of anonymity.
In a related development, police in Pakistan's Punjab province said Thursday they had captured three men who were allegedly trained by India's main intelligence agency, known as RAW or Research and Analysis Wing, to carry out terrorist attacks inside Pakistan.
Pervaiz Rathore, chief of police in the Punjabi capital city of Lahore, said the three men had been captured from a Pakistani village close to the Indian border. No further details were available.