Mass murderers who were already well-known before their killings?

Philip Adams was a professional footballer for multiple teams such as the Oakland Raiders and the San Francisco 49ers before killing 6 people and then himself in the Rock Hill Massacre. It was later discovered that he had developed Chronic Traumatic Encephalopathy during his football career.

Frazier Glenn Miller Jr. was already a somewhat well-known figure in far-right/white-nationalist politics before committing the Overland Park Jewish Community Center shooting. He notably founded the White Patriot Party and had attempted to run for several public office positions, occasionally as a write-in candidate.

Elliot Rodger had been posted on several cringe-sharing communities on iFunny and Reddit before committing his now infamous massacre, his reputation got to the point that he had to take down many of his videos so people would stop making fun of him, he also had a reputation on bodybuilding.com.

Dipendra Bir Bikram Shah Dev was the Prince of Nepal when he killed his father, King Birendra, his mother, Queen Aishwarya, and 7 other members of his family in a mass shooting. After shooting himself, he was put in a medical coma for 3 days, in which he was officially recognized as King of Nepal. His uncle, Gyanendra Bir Bikram Shah Dev, became the official King of Nepal.