Just before Christmas 1975, American CIA station chief Richard Welch was shot at point blank range outside his Athens residence as he and his wife arrived home from a holiday party. Welch was the first CIA agent ever killed by terrorists, and his murder spurred a number of policies, which are still in effect today, to protect the identity of American spies. Welch’s assassination was also the first casualty claimed by the Athens-based “Revolutionary Organization 17 November,” known as 17N. The urban guerrilla organization went on to claim responsibility for the deaths of 23 people in more than 100 attacks on American, British, Turkish and Greek targets. They disbanded in 2002 when their leaders, including Christodoulos Xeros, were jailed. Xeros was sentenced to six life sentences for his responsibility in masterminding the deaths of Americans, Britons and Greeks.

On January 1, Xeros, 56, who had been serving his time in Athens’ Korydallos Prison, disappeared after failing to check in with local authorities during an approved holiday furlough. On Monday, he issued a video message, calling on his comrades in hiding to “reunite to protest the repercussions of three years of economic austerity in Greece.” In the message, which was broadcast on Greek television, he vowed to return to arms. “It’s time for battle,” he said. “I’ve decided to fire the guerrilla shotgun against those who stole our lives and sold our dreams for profit.” In response the Greek government offered a $5.4 million bounty on his head—dead or alive.

The furlough from which Xeros escaped was the sixth he had been granted under a program that allows prisoners serving life sentences to have a little time out from behind bars after they have served at least eight consecutive years in prison. Xeros is now the target of a nationwide manhunt in Greece, amid fears that he has joined forces with other militant groups, including the notorious Conspiracy of the Cells of Fire group that claimed responsibility for a series of parcel bombs delivered to foreign embassies in Athens in 2010 amid a government meltdown.

Authorities in Greece are now concerned that Xeros is offering crucial training in explosives to the younger Conspiracy group in exchange for safe haven. According to authorities in Greece investigating Xeros’s disappearance, the elder terrorist had been in “frequent” and “close” contact with Conspiracy of the Cells of Fire inmates. Frangiskos Ragousis, an attorney who represented Xeros in 2002, who claims he has not been in touch with his client for several months, speculated that Xeros was making a political statement. “It is a political decision in line with his revolutionary activity,” he told Greek SKAI television.

The disappearance prompted the U.S. State Department to issue a statement on the matter. “We are deeply concerned that the convicted for terrorist acts Christodoulos Xeros who was a key member of the terrorist organization November 17, that killed five employees of the U.S. Mission to Greece, has violated his furlough and is now disappeared,” it said in a statement. “We are engaged with Greek officials on this case. We call on the Greek government to locate Xeros and return him to prison.”

The scant clues involving Xeros’s disappearance include the car he used and then abandoned outside of Athens and a flurry of telephone calls to relatives who apparently helped fund his getaway. Authorities also concede that there is now evidence that Xeros had been planning his escape since last summer, when he first qualified for the furlough program.

As the manhunt continues, Greek authorities are questioning the sanity of a prison furlough system that allows terrorists serving multiple life terms to temporarily leave jail. “The benefit of prison leave can’t be turned into a means to undermine the country’s crime-fighting policies,” Greek Justice Minister, Haralambos Athanassiou, said in a statement on Greek television last week.

Further speculation that Xeros’s escape could have political ramifications across the country were bolstered with the resignation of Petros Tastopoulos, a parliamentary member of the opposition SYRIZA party, who claimed leaders within his party were sympathetic towards the N17. “There are people within SYRIZA who may be sympathetic to the ideas of these people,” Tatsopoulos said when he resigned. “I assume that because of their own statements, that they considered Xeros a political prisoner.”

The terrorist’s easy escape comes just as Greece assumes the six-month rotating presidency of the European Union.