Complex sentence: In the weeks leading up to BEA's preliminary report, the investigation into Lubitz revealed he had been treated for suicidal tendencies prior to his training as a commercial pilot and had been temporarily denied a U.S. pilot's license because of these treatments for depression.
Split into simpler sentences: In the weeks leading up to BEA's preliminary report, the investigation into Lubitz continued. He had been treated for suicidal tendencies prior to his training as a commercial pilot and had been temporarily denied a U.S. pilot's license because of these treatments for depression.