Mathinthiran was leaving the headquarters of the Tamil Coordination Committee (CCT) in the east of Paris when the assassin shot several 9mm-calibre bullets into his groin and back.
The LTTE has been accused of raising “revolutionary taxes” from the Tamil diaspora to finance its guerrilla struggle.
Mathinthiran, who had acquired French nationality, was sentenced to five years in prison in February for extortion, financing terrorism and being part of a criminal gang.
He had already served three years of his sentence after making a deal with the authorities.
The court also banned the CCT, declaring that it was a front organisation for the LTTE, which the European Union and the US categorise as a “terrorist organisation”.
Mathinthiran’s lawyer Gilles Piquois has accused “Tamil collaborators” with the Sri Lankan government of being behind the killing,, adding that his client had already been attacked in the same place a year ago.
An investigation has been opened.
The killer Mathinthiran fled the scene and has not yet been arrested.
Paris has a well established Tamil community, coming from both Sri Lanka and southern India, much of it centred on streets near the Gare du Nord railway station.