Complex sentence: Because Wesbecker had started taking Prozac in August 1989--less than a month before the shooting--the wounded and the families of those killed filed a lawsuit against manufacturer Eli Lilly and Company, claiming that Wesbecker's use of Prozac contributed to his actions.
Split into simpler sentences: Because Wesbecker had started taking Prozac in August 1989, less than a month before the shooting. The wounded and the families of those killed filed a lawsuit against manufacturer Eli Lilly and Company, claiming that Wesbecker's use of Prozac contributed to his actions.