Omer Guney, 30, was charged with the triple murder on Monday. French authorities initially described him as an ethnic Kurd who had acted as an occasional driver for the most prominent victim, Sakine Cansiz, a co-founder of the outlawed Kurdistan Workers Party (PKK).
Police sources said Guney himself had told them he had been a member of the PKK for two years, fueling suspicions that the brutal murders had been the result of an internal feud in the organisation.
That was denied by the PKK, while a Kurdish group in Paris said the alleged killer had faked his Kurdish identity to infiltrate the activist community in Paris from November 2011 onwards.
"After his arrest, we discovered that he was not Kurdish, as he had pretended, but was in fact a Turk from the Sivas region and the product of a family with links to the Turkish nationalist extreme right," a statement from the Kurdish Information Centre in Paris said.
Judicial sources indicated that the French authorities continue to regard Guney as being Kurdish, having been born to a Kurdish father and a non-Kurdish mother. He was born in Sarkisla, an ethnically mixed town in the Sivas region.
A PKK leader said there was no way Guney could have been a member of the group, which is considered a terrorist organisation by Turkey and its allies and defended as a national liberation movement by its supporters.
"The allegations on the suspect's ties with the PKK do not reflect the truth," Murat Karayilan, who heads the PKK in the absence of its jailed leader Abdullah Ocalan, told the pro-Kurdish Firat news agency at his base in northern Iraq.
"It is not that easy to be a member of the PKK in two years," Karayilan said. "PKK does not accept members from Europe in this way. The mentioned person is not a member of our movement and he is not known by our side or by our executives in Europe."
The rebel leader said he had no doubt Turkey was involved in the killing and that Ankara was well known for infiltrating the Kurdish movement with agents.
The killings came against a background of tentative peace talks betweenTurkey and jailed PKK leader Ocalan aimed at ending three decades of conflict which have claimed 45,000 lives.
Turkey has suggested that the murders bore the hallmarks of an internal feud within the PKK between opponents and supporters of the negotiations with Turkey.
French police have insisted all possible motives are being examined, including a personal dispute and a possible link to extortion rackets used to raise funds for the PKK.