Simplify the following text for a Grade 6 native English-speaking person.
Original: The El Gato Negro characters were created by comic book artist and writer Richard Dominguez , both making their first published appearance in El Gato Negro # 1 ( October 1993 ) published under Dominguez 's own Azteca Productions imprint . The original series followed the adventures of Francisco Guerrero , a social worker living in Edinburg , Texas and grandson to the original El Gato Negro , who adopted his grandfather 's former nom de guerre in order to avenge the death of his best friend .
Simplified: Francisco became the new El Gato Negro after the murder of his friend .