Tunisian opposition figure Mohamed Brahmi was gunned down with the same weapon used to kill another opposition politician earlier this year, Interior Minister Lotfi Ben Jeddou said on Friday.
Brahmi was killed with the same weapon used to murder Chokri Belaid in February, he told a news briefing.
"The gun used to kill Mohamed Brahmi is the same as that used to kill Chokri Belaid," six months earlier, he said.
Ben Jeddou said the main suspect in the Brahmi killing was a member of the radical Sunni Muslim Salafist movement.
"The first elements of the investigation show the implication of Boubaker Hakim, a Salafist extremist," he said, a day after Brahmi was gunned down outside his home near Tunis by two gunmen on a motorcycle.
Ben Jeddou called Hakim "among the most dangerous terrorists, who is being hunted internationally".
The 30-year-old Paris-born suspect was already wanted in Tunisia for kidnapping and arms trafficking, the interior minister said.
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Hakim was also on the run after a recent police raid on the building where he had been staying.
"He took flight, leaving behind his personal possessions and a quantity of weapons," said public security chief Mustapha Taieb Ben Amor.
"Firearms, two home-made bombs, ammunition, a revolver and knives were seized," he added.
Ben Amor named 14 radical Islamist suspects -- including four behind bars -- implicated in the two political killings.
A day before Brahmi's murder, a senior adviser to the prime minister said six people believed to have orchestrated Belaid's killing had been identified.
Replying to a question on Friday, the interior minister ruled out the involvement of political parties in the murders of Belaid and Brahmi.
"The investigation has not shown this -- We have no elements at our disposal proving the implication of a political party," Ben Jeddou said.
"The suspects are radical extremists, and some of them belong to Ansar al-Sharia," the main Salafist group in Tunisia, he said.