Athens protests that there is no Macedonian minority within its borders. The government fears the Slavic-Macedonian community in Greece, which numbers between 50,000 and 300,000, depending on who is counting, could seek political links with ethnic kin in the Former Yugoslav Republic of Macedonia.
Greece is so concerned with the growth of Slavic-Macedonian consciousness that it recently introduced an economic blockade on its neighbour. Athens claims the exclusive right to the name Macedonia, and claims that it has been usurped by Slavic speakers from the former Yugoslavia.
The threats against Anastasia Karakasidou, 38, escalated last week when Stohos, an extreme right-wing Greek newspaper, published her address in Salonika. The newspaper also provided details of the car she uses while researching Macedonian-speaking villages in the northern Greece. Ms Karakasidou does not believe that the government is behind the death threats, but feels that the threats are the work of nationalist extremists.
So as not to stir controversy over the Macedonian debate in Greece, she decided not to publish her dissertation, Fields of Wheat, Hills of Shrubs, Agrarian Development and Nation Building in Northern Greece.
Greek newspapers got their hands on the manuscript anyway. Since then, Ms Karakasidou, the mother of two young children, has been mercilessly hounded by sections of the Greek media and by the Greek-American community in the United States.
She received a veiled death threat from a Greek-American newspaper in February, when it published an article describing a possible scenario for her death. It described an attack by a group of men, one of whom pushed a stick painted in the colours of the Greek flag into her heart, killing her as a traitor. It is thought that the veiled death threats were designed to frighten her away from academic research. In the US, Greek nationalists unsuccessfully lobbied to prevent Ms Karakasidou being given an assistant professorship at the City University of New York. In Salonika the secret police have ostentatiously visited her elderly mother.
The Greek Macedonian community refuses to go away, despite attempts to deny its existence. Efforts to stamp out use of the Macedonian language, by refusing to open Macedonian schools or allow the publication of newspapers in the language, have failed.
The government has changed the names of hundreds of Macedonian villages into Greek-sounding names. The closest it comes to recognising the community is to call them 'Slavophone Greeks' or 'bilinguals.'
Ethnic Macedonians say that they are a people of Slavic descent, who speak Macedonian, and have a culture and customs which differ from the Greek majority.
The geographic region of Macedonia is divided among Bulgaria, Greece and the newly independent country of Macedonia. According to anthropologists, the Greek portion has two distinct groups - the ethnic Macedonians who settled around the sixth century - and the Greeks, many of whom are descendants of refugees from Asia Minor, who arrived during the 1920s.
The population of Greek Macedonia has changed since the Balkan wars, when thousands of Macedonians left for Bulgaria. Many more left as political refugees during the 1946-49 Greek civil war. Since then, those who consider themselves Macedonian - even though born in Greece - have not been allowed back.
Tomorrow: Political trials in Greek Macedonia