Simplify the following text for a Grade 8 native English-speaking person.
Original: On the morning of April 1 , 1984 , Marvin and his father got into an argument after his father verbally assaulted Marvin 's mother while they were arguing over misplaced business documents .
Simplified: On April 1 , 1984 , Gaye 's father fatally shot him after an argument that started after his parents squabbled over misplaced business documents . Gaye attempted to intervene , and was killed by his father using a gun that Marvin Jr. had given him four months before .