MONTCADA, Spain -- Three months after the Germanwings jet crashed in the French Alps, about 500 tearful mourners packed a funeral home Saturday to say goodbye to Robert Oliver Calvo, who was on his last regular business trip abroad before a work change that would have kept him home more.

The father of two small children and the only child of his parents was remembered in an auditorium by the standing crowd as a deeply religious and dedicated family man, who had been on a business trip abroad for the Barcelona-based clothing store chain Desigual.

The only mention of the crash itself during the service in the hilly Barcelona suburb of Montcada was in the funeral program, which said he died at age 36 "in the airplane tragedy in the Alps on the Germanwings Airbus A320 owned by Lufthansa."

"This is the worst thing that can happen to a father and a mother: Lose a loved one," Oliver Calvo's father, Robert Tansill Oliver, said in an interview after the memorial service -- the only one so far for a victim of the plane crash that the media have been allowed to attend.

Oliver Calvo had worked for years as a real estate manager for a successful company that bucked Spain and Europe's financial crisis with store openings galore, and his job was to travel to countries like Austria, Germany, Poland and Switzerland for mid-week trips lasting three to four days to make sure the openings went off without a hitch.

On March 24, he was on his way to open a new Duesseldorf store when the plane's co-pilot Andreas Lubitz locked the pilot out of the cockpit and deliberately crashed it into a mountain. The trip was supposed to be Oliver Calvo's last before a promotion that would have kept him involved in the chain's real estate business but travelling nowhere near as much.

"He just didn't want to be on the road so much. He had been travelling all over Europe for years and now he wasn't going to be travelling every week or every other week so he could spend more time with his family," friend Luis Anera, who led the memorial service, said in an interview.

Tansill Oliver and many others at the funeral home read aloud from the Bibles they brought to the funeral service. He said the family finds some solace because they are Jehovah's Witnesses and are convinced that Oliver Calvo will be resurrected.

His son's remains were among those of 32 victims sent to Spain this week after the remains of German victims were sent home earlier. In all, 150 people died in the plane crash -- most of them German or Spanish.

Tansill Oliver said after the service that the crash investigation must answer how Lubitz managed to continue flying despite visiting dozens of doctors in the five years he had been working for the low-cost division of Lufthansa.

And he urged people who may have known Lubitz to contact authorities in the hope that their observations about his behaviour might help explain what caused him to crash the Germanwings flight and what warning signals might have been missed before he did so.

"It's hard for me to believe something didn't happen during one of his other flights and no one noticed," he said.

Lubitz, who had a history of depression, had seven medical appointments in the month before the crash, including three with a psychiatrist, and had taken eight sick days off work, a French prosecutor has said.

Some of the doctors felt Lubitz was psychologically unstable, and some felt he was unfit to fly, but didn't report that information to anyone because of medical secrecy laws.

Before the crash Lubitz searched on the Internet in March for ways of getting hold of the toxic compound potassium cyanide, tranquilizer valium and lethal combinations of medicines.

Tansill Oliver said he was hopeful that a reason why Lubitz avoided detection would be discovered by a panel three French investigating magistrates appointed this week to lead a criminal probe into whether any other person, company or public agency might be liable.

Pinpointing liability will help families and Lufthansa determine how they can compensate surviving relatives of the victims and set up safeguards to prevent a repeat of the Germanwings crash, Tansill Oliver said.

Whoever ends up being responsible "needs to take the necessary steps so this kind of tragedy never happens again to anybody," he said.