ATHENS — When Socrates Giolias, a little-known journalist and blogger, was killed outside his home in a gangland-style shooting early Monday, homicide detectives began to work on the case amid speculation that it was a reprisal by shady underworld figures.
But several hours later, counterterrorism officers joined the investigation after tests on the cartridge cases of the 16 bullets fired at Mr. Giolias were linked to weapons used in attacks by Greece’s deadliest active guerrilla group, the Sect of Revolutionaries.
Now the killing has led the authorities to fear a resurgence of domestic terrorism, a scourge that has haunted Greece since the early 1970s and that has seen a gradual revival over the past year and a half with the emergence of several new militant organizations.
An official at the Greek police headquarters, which itself became a target last month when a letter bomb killed the assistant to the public order minister, confirmed Tuesday that the force was treating the murder of Mr. Giolias as a terrorist act.
The official, who was not authorized to speak publicly, gave no details about the investigation but simply stated that the 16 cartridge casings found at the scene of the shooting had been fired from two 9-millimeter pistols used in previous attacks in Athens claimed by the Sect of Revolutionaries: the slaying of police officer in June last year and two attacks four months earlier, one on a police station and the other on a private television channel.
Killings of journalists are rare in Greece. The last was in 1985, when the Marxist guerrilla group November 17, now disbanded, shot Nikos Momferatos, publisher of a conservative newspaper.
But the Sect of Revolutionaries had warned that journalists were on its hit list. In a proclamation issued in February last year, the group accused the media of “manufacturing news to keep the public docile and subservient.”
“Journalists, this time we came to your door, next time you will find us in your homes,” the document said, referring to the armed attack on the private television channel, in which no one was hurt.
The reason that Mr. Giolias was a target remains unclear, although some Web sites have linked him to comments critical of militant groups. Angelos Tsigris, a professor of criminology at Greece’s police academy, said Mr. Giolias might have been singled out because he did not employ bodyguards like many of Greece’s prominent investigative journalists, with whom he had cooperated. “They might have chosen him because he was an easy target,” Mr. Tsigris said.
Mr. Giolias, head of news at Thema, a private radio station, and one of the journalists behind the dirt-digging news blog Troktiko, was shot in Ilioupoli, an eastern suburb of Athens, at 5:30 a.m. on Monday. A witness quoted by state television said she had seen the killers wearing bulletproof vests and uniforms reminiscent of private security firms.
One of the group buzzed the intercom to Mr. Giolias’s apartment and told him that thieves were trying to break into his car, according to statements made later to the police by his wife. The journalist, taking the bait, came down and was showered with bullets as he opened the main door to the building.
Neighbors told state television that they saw Mr. Giolias’s wife, who is pregnant with their second child, emerge onto the balcony screaming.
On Tuesday, readers posted hundreds of messages on Troktiko, which claims to attract six million visitors daily. Entries referred to Mr. Giolias as a “hero” or an “intrepid and daring journalist.”
Other contributors lamented the implications of the murder. One said: “Is this the Greece we dreamed of? Are we prey to paid killers?”
Describing Mr. Giolias as “insubordinate, free and independent,” colleagues suspended the blog to attend his funeral Tuesday afternoon.
Troktiko had drawn stinging criticism from other anonymous bloggers when it published disparaging comments about Revolutionary Struggle, a more established terrorist organization, after six people suspected of being members of the group were arrested in April; that group is best known for firing a rocket-propelled grenade at the U.S. Embassy in Athens in January 2007.
Anarchist Web sites have also said Mr. Giolias was responsible for scathing comments about the Sect of Revolutionaries that were posted on Troktiko last year but quickly removed.
While some officials say the latest attack could signal a return of domestic terrorism, some analysts drew a distinction between the style and methods of the Sect of Revolutionaries and the type of terrorism that flourished in Greece in the 1970s and 1980s, chiefly the attacks of November 17, which cited Marxism as its driving influence.
The Sect of Revolutionaries’ proclamation bluntly states its stance: “We are not interested in politics, but guerrilla warfare.”
Mr. Tsigris, the criminologist, said what worried him most was that Sect of Revolutionaries was just one of several militant groups, many of which formed early last year in reaction to the killing of a teenager by a police officer in December 2008.
These groups have “different outlooks, goals, methodology,” which complicates the task faced by the Greek police, he said.
“Monday’s attack shows that terrorism is alive and kicking in Greece today,” he said, “as it was yesterday and the day before.”