The trial could begin by early September and if it concludes "relatively quickly" the marines could be home for Christmas, Staffan de Mistura said on his return from meetings with Indian officials in New Delhi.
"I'll do anything to make it happen," Italian news agency ANSA quoted de Mistura as saying.
While in New Delhi, the envoy also told Indian authorities that four other Italian sailors who were witnesses to the shootings of the fishermen would not be available for interviews by investigators in the case.
The two marines -- Salvatore Girone and Massimiliano Latorre -- were arrested on February 19 last year four days after they shot and killed two fishermen off Kerala coast on February 15, allegedly mistaking them for pirates. Both are facing murder charges.
Italy had claimed since the incident had taken place in international waters, Indian courts have no jurisdiction to conduct the trial.
However, the Supreme Court had ruled that the incident took place at a distance of about 20.5 nautical miles from the coastline of Kerala and, therefore, it occurred not within the territorial waters of the coastline of Kerala state but within the Contiguous Zone.
Italy's previous decision not to send marines to face trial had triggered a diplomatic standoff, with the Indian Supreme Court barring the Italian ambassador from leaving the country.
Image: Salvatore Girone and Latorre Massimiliano are escorted as they leave a courtroom at Kollam
Photograph: Sivaram/Reuters