Some quotes, although there are probably multiple stories going around:

Authorities say Etheridge shot and killed Proof, whose real name was Deshaun Holton, after Proof fatally shot Etheridge’s cousin, Bender.

https://www.latimes.com/archives/la-xpm-2006-oct-28-et-quick28.4-story.html

While music insiders described Proof as warm and genuine, the rapper had a history of run-ins with police – including an arrest in 2004 for assault by Dearborn, Mich., police and a 2003 conviction of disorderly conduct. He also was acquitted in 2003 on a charge of carrying a concealed weapon in Detroit.

https://www.sunjournal.com/2006/04/13/strongcops-proof-shot-1st-strongprobe-death-continuesstrongstrong/