A French police official says European investigators are focusing on the psychological state of the 27-year-old German co-pilot who deliberately smashed an Airbus carrying 150 people into an Alpine mountainside.

Returning Monday from a meeting with counterparts in Germany, judicial police investigator Jean-Pierre Michel told The Associated Press that authorities want to find out "what could have destabilized Andreas Lubitz, or driven him to such an act."

Lubitz was the co-pilot of Germanwings Flight 9525, which slammed into a mountain near Le Vernet, France, last week en route from Barcelona, Spain, to Duesseldorf, Germany.

Germanwings chief operating officer Oliver Wagner was meeting with relatives of the victims Monday in the southeastern French city of Marseille. He said a total of 325 family members have come to France.