The DNA of 78 victims on board Germanwings Flight 9525 has been isolated, investigators said Sunday, denying claims that the body parts of co-pilot Andreas Lubitz had been identified. The Airbus A320 crashed into a mountainside in the French Alps last Tuesday, killing all 150 people on board.

Investigators have so far retrieved 600 body parts from the crash site, with some being as small as the size of a postage stamp, media reports said. Michael Tsokos, a German forensic scientist, told local newspaper Bild that authorities believe 95 percent of the victims would be identified in three weeks following which they will officially be declared dead. However, investigators denied German media reports that the DNA of Lubitz, who is alleged to have induced the crash, had been identified.

Recovery teams are continuing to search for human remains as well as parts of the aircraft, including the flight data recorder, BBC reported. Last week, the New York Times had reported that the casing of the second black box had been recovered but the memory card in it was missing.

A road to the crash site, which is located in rough terrain, is being built and is expected to be completed by Monday evening, Marseille prosecutor Brice Robin reportedly said. Crew members had to rely on helicopters, climbing gear and local mountaineers to access the remote area in Seyne-les-Alpes, rendering the recovery operations a challenge.

Meanwhile, a transcript of the plane’s cockpit voice recorder published by Bild revealed Captain Patrick Sondenheimer shouting, "Open the goddamn door," as he tried to break into the locked cockpit. A conversation between the captain and Lubitz -- shortly after the flight took off from Barcelona for Dusseldorf -- indicated that the co-pilot encouraged Sondenheimer to use the toilet.

Investigators, who are trying to determine why Lubitz might have intentionally caused the crash, have revealed that the 27-year-old had sought medical treatment for problems with his vision. Reports also claimed that he was suffering from a detached retina, potentially jeopardizing his ambition to fly long-haul routes for Germanwings' full-service parent, Lufthansa.

Authorities had found antidepressants in Lubitz's house along with evidence of treatment by various doctors, including a torn-up sick note signing him off work on the day of the crash.