The 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 state prosecutor has said – a revelation that suggested Andreas Lubitz was seeking advice about an undisclosed ailment.

Meanwhile, the families of 30 of the 150 people killed in the crash received long-awaited news on Friday that they will start receiving bodies next week. Others, however, will have to wait to receive remains or their loved ones’ belongings.

Marseille prosecutor Brice Robin, who is leading a criminal investigation into the 24 March crash that killed all 150 people on board Germanwings flight 4U9525, said he had received information from foreign counterparts and was going over it before a meeting with victims’ relatives in Paris next week.

In that closed-door meeting at the French foreign ministry on 11 June, Robin will discuss his investigation and efforts to reduce administrative delays in handing over the victims’ remains to grieving families, his office said on 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.

Robin said late on Thursday that Lubitz had also reached out to dozens of doctors in the period before the crash. That suggested Lubitz was desperate to find an explanation for some mental or physical ailment, even as he researched ways of killing himself and others. Robin would not address the question of what symptoms Lubitz was assessing.

Germanwings and its parent company, Lufthansa, had no comment on Friday on the finding, citing the ongoing investigation. Prosecutors have previously said they found torn-up doctors’ notes excusing Lubitz from work at his home, including one covering the day of the crash, and that he appeared to have hidden his illness from his employer and colleagues.

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

Relatives of victims were not informed that Lubitz had seen so many doctors, said Robert Tansill Oliver, a retired American teacher living in Barcelona, whose 36-year-old son Robert Oliver Calvo died in the crash.

The development, combined with news that remains of some victims can’t be sent home next week as originally planned, was “devastating, just devastating”, Oliver said.

“Every time we see news like this it’s like another plane crash,” he said. He said relatives were informed this week that they would not be able to view the belongings of the victims next week in Paris, as was originally promised, and might need to wait until September.

The prosecutor 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 agonising waits for many families.

Earlier this week, plans to repatriate the remains of the victims had been put on hold because of errors on death certificates. However, Elmar Giemulla, a lawyer representing several German families, said some of them were informed on Friday that the repatriation would go ahead as planned 10 June.

Lufthansa said on Friday that an MD11 plane would transport the remains of 30 victims from Marseille to Duesseldorf on Tuesday, and they would be handed over to relatives on Wednesday.

Further remains will be transported to the victims’ homelands over the coming weeks, it said.

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.