Investigators picking through the wreckage of a passenger jet that crashed on a remote Alpine mountain said they had found DNA from more than half of the victims, as more details emerged concerning the doomed flight's last minutes.
Forensic teams announced they had isolated almost 80 distinct DNA strands from body parts at the Germanwings crash site in the French Alps, as recovery personnel continued their grim task following last week's tragedy.
French officials say the plane's black box voice recorder indicates that co-pilot Andreas Lubitz, 27, locked the captain out of the cockpit of the Airbus jet and deliberately crashed Flight 4U 9525, bound for Duesseldorf from Barcelona.
Investigators have described the difficulty searching for bodies and a second black box as "unprecedented" due to a combination of mountainous terrain and the violence of the impact.
The plane is said to have crashed at a speed of 700 kilometres (430 miles) per hour, killing all 150 on board instantly.
Prosecutor Brice Robin, one of the lead investigators, said an access road was being built to the site to allow all-terrain vehicles to remove some of the larger parts of the plane and help transport bodies.
He said forensic experts had identified 78 different DNA strands.
"We haven't found a single body intact," said Patrick Touron, deputy director of the police's criminal research institute.
"We have slopes of 40 to 60 degrees, falling rocks, and ground that tends to crumble. "Some things have to be done by abseiling. Since safety is key, the recovery process is a bit slow, which is a great regret," he added.
Most body parts were being winched up to helicopters and transported to a lab in the nearby town of Seynes, where a 50-strong team of forensic doctors, dentists and police identification specialists is working.
Between 400 and 600 body parts were being examined, Touron said.
"In catastrophes, normally around 90% of identifications are done through dental records," he added, but in the case of flight 9525, DNA was likely to play a greater role than normal.
Once DNA samples have been taken, they are sent to another lab outside Paris where they are compared with samples taken from family members this week.
Second black box 'priority'
Captain Yves Naffrechoux, a mountain ranger, said finding the second black box -- the flight data recorder which logs all technical data -- was a priority.
Germany's Bild newspaper on Sunday reported more details of the flight's final moments.
It said the captain, which it identified as Patrick S., shouted at the co-pilot to "open the damn door" as he desperately tried to get back into the locked cockpit after leaving to use the toilet.
"For God's sake, open the door" he yelled as passengers' screams could be heard in the background, it said, citing information from the cockpit voice recorder.
Bild said "loud metallic blows" against the cockpit door could then be heard, before another warning alarm went off.
As investigators seek to build a picture of Lubitz and any possible motives, media reports have emerged that he suffered from eye problems, adding to earlier reports he was severely depressed.
German prosecutors believe Lubitz hid an illness from his airline but have not specified what it was, and said he had apparently been written off sick on the day the Airbus crashed.
The Bild tabloid and the New York Times have reported that Lubitz had sought treatment for problems with his sight.
Police have found a number "of medicines for the treatment of psychological illness" during a search at his Duesseldorf home, Welt am Sonntag newspaper said.
It added that the Germanwings co-pilot was suffering from stress and severe depression, according to personal notes found.
German prosecutors revealed Friday that searches of Lubitz's homes netted "medical documents that suggest an existing illness and appropriate medical treatment", including "torn-up and current sick leave notes, among them one covering the day of the crash".
A flight attendant told Bild she had a relationship with Lubitz last year and recalled him saying: "One day I'm going to do something that will change the whole system, and everyone will know my name and remember."
Bild also reported that Lubitz's girlfriend with whom he lived was believed to be pregnant.
French police investigator Jean-Pierre Michel told AFP Saturday that Lubitz's personality was a "serious lead" in the inquiry but not the only one.
Lufthansa CEO Carsten Spohr has said that Lubitz had suspended his pilot training, which began in 2008, "for a certain period" before restarting and qualifying for the Airbus A320 in 2013.
The second-in-command had passed all psychological tests required for training, Spohr said.
Half of the victims were German, with Spain accounting for at least 50. The remainder were a mix of more than a dozen other nationalities.