The official French inquiry calls for suspect Omer Guney to be sent to trial for involvement in a terrorist enterprise for the murder of Sakine Cansiz, 54, Fidan Dogan, 29, and Leyla Seylemez, 25, at a Kurdish culutral centre in Paris in 2013.
Guney, who denies the charges, posed as a fervent PKK supporter himself, but his friends said he was a right-wing Turkish nationalist and the inquiry found that he had frequent contact with the Turkish secret services, the MIT, according to Le Monde newspaper.
"Numerous elements allow us to suspect the implication of the MIT in the instigation and preparation of the murders," its report says.
But, it adds, that it was unable to establish whether MIT agents acted on official orders or without their bosses' knowledge in order to sabotage the peace process.
The investigation found that Guney, who asked for the Turkish embassy to be alerted when he was arrested, made several trips to Turkey in the six months before the murders.
There he used a "secret" telephone line to contact certain people, one of whom could not be identified because the Turkish authorities refused to allow the investigators to interview him.
Leaks in the Turkish press have backed up the thesis of MIT involvement.
Last year Erdogan himself accused US-based preacher, Fethullah Gulen, of having "committed a series of murders in Paris" so as to "sabotage" the peace process.
Gulen, who had a network of supporters in the Turkish state, backed Erdogan in his rise to power but split with him before the last election, leading to a purge of the police and judiciary.
This is the first time a French inquiry has named a foreign secret service in connection with murders committed on French soil.