A state prosecutor says a co-pilot with a history of depression who crashed a Germanwings airliner into the French Alps had reached out to dozens of doctors ahead of the disaster, a revelation that suggests Andreas Lubitz was seeking advice about an undisclosed ailment.

Marseille prosecutor Brice Robin, in comments to The Associated Press, would not address the question of what symptoms Lubitz was assessing.

Robin, who is leading a criminal investigation into the March 24 crash that killed all 150 people on board Germanwings Flight 9525, said he has received information from foreign counterparts and is going over it before a meeting with victims' relatives in Paris next week.

In that closed-door meeting at the French Foreign Ministry on June 11, Robin will discuss his investigation and efforts to reduce administrative delays in handing over the victims' remains to grieving families, his office said Friday. Those remains are still in Marseille, frustrating some families.

Investigators say Lubitz intentionally crashed the jet after locking the pilot out of the cockpit. German prosecutors have said that in the week before the crash, he spent time online researching suicide methods and cockpit door security -- the earliest evidence of a premeditated act.

Late Thursday, Robin told the AP that Lubitz had also reached out to dozens of doctors in the period before the crash, without elaborating. That suggests Lubitz was desperate to find an explanation for some mental or physical ailment, even as he researched ways of killing himself and others.

Germanwings and parent company Lufthansa have said that Lubitz had passed all medical tests and was cleared by doctors as fit to fly.

Robin said he had received responses to a formal French request for international cooperation in his probe, including from Germany -- home to about half of the victims, and to Germanwings and its parent company Lufthansa. Robin said he would address the media after thoroughly examining the responses and meeting the families next week.

For now, "I have decided to prioritize the victims' families," he said.

Robin also noted delays in embalming the remains of the victims, which he said must be done according to the national rules of each of the 19 countries the victims came from. That complex process has prompted agonizing waits for many families.

In the meeting with families, Robin plans to go over the discovery of DNA evidence and the reconstitution of the remains, and explain the details of handing them over to loved ones, his office said. Local officials near the crash site have already signed needed authorizations for burials to proceed.

A lawyer representing several German families has said anger is growing because errors in official death certificates have stalled the repatriation of the remains of those killed. Many relatives had intended to start burying their loved ones next week.