Complex sentence: After the incident, police focused their investigation on one of the victims, Yoshiyuki Kōno, whose wife was put in a coma by the gas, when they discovered that Kōno had stored a large amount of pesticide in his residence.
Split into simpler sentences: After the incident, police focused their investigation on Yoshiyuki Kōno, whose wife was a victim put in a coma by the gas. It was discovered that Kōno had stored a large amount of pesticide in his residence.