Indian national Kulbhushan Sudhir Jadhav was born in the city of Sangli in the Indian state of Maharashtra on Aug 30, 1968, according to a copy of a passport belonging to him under the pseudonym Hossein Mubarak Patel.
The cover name, he explained in a confessional video released by Inter-Services Public Relations last year, was taken for "intelligence gathering for Indian agencies".
A resident of Mumbai's suburban Powai neighbourhood, Jadhav belongs to a family of police officers.
In his statement, the Indian national said he is currently a serving officer in the Indian Navy ─ a claim India has denied.
He added that he joined the National Defence Academy in 1987, and then the Indian Navy in 1991, where he served until December 2001.
After the parliament attack, he said he began to 'contribute his services' towards information and intelligence gathering in India.
"I am still a serving officer in the Indian Navy and will be due for retirement by 2022 as a commissioned officer in the Indian Navy," the spy confessed.
India says he is a former Indian Navy officer.
Members of his Mumbai-based family told The Indian Express last year that Jadhav had become a businessman after taking premature retirement from the Navy, and travelled often in connection with his business.
A report in DNA India claimed Jadhav was "engaged in a legitimate business of operating ferries from the Iranian port town of Bandar Abbas".
Jadhav said he had commenced intelligence operations in 2003, and established a business in Chahbahar, Iran, where he was able to go undetected and visit Karachi in 2003 and 2004.
He was picked up by Indian spy agency Research and Analysis Wing at the end of 2013, and has been directing various subversive activities in Karachi and Balochistan.
His job, he said, was to hold meetings with Baloch insurgents and collaborate with them to carry out activities "of a criminal nature, leading to the killing or maiming of Pakistani citizens."
Jadhav, in pursuit of targets set by his RAW handlers, was arrested by Pakistani authorities on March 3, 2016, when he attempted to cross over into the country from the Saravan border in Iran.
India, however, alleges that Jadhav was abducted by Pakistan from Iran, according to IndiaToday.
Indian intelligence officials suspected that Jadhav's phone was under surveillance by the Pakistani intelligence, and that his habits and mannerisms, including phone calls in Marathi to his family, gave away his identity.
Since Jadhav's arrest, India has been denied consular access to him, although he was provided with a defending officer as per legal provisions during his Field General Court Martial trial.
He was sentenced to death by the FGCM on April 10, 2017.