Complex sentence: Following Cheurfi's identification, three members of his family were arrested in Chelles in the early morning of April 21, although investigators believe Cheurfi acted alone and was inspired by ISIS but was not necessarily a member.
Split into simpler sentences: Following Cheurfi's identification, three members of his family were arrested in Chelles in the early morning of April 21. However, investigators believe Cheurfi acted alone and was inspired by ISIS but was not necessarily a member.