The suspect, Michael Williams, allegedly killed Barnes' 48-year-old aunt Tanganyika Hoover by slashing her throat.
The two were estranged but staying together at a friend's house when Hoover was found outside with her neck cut.
Barnes asked his Twitter and Instagram followers to look for Williams, the only suspect in the case.
This dude stabbed my auntie in the neck last week & left her for dead on the sidewalk, she ended up... http://t.co/nHIczsJdrG— Matt Barnes (@Matt_Barnes22) July 22, 2014
The strategy worked and Williams was arrested after someone called in a tip.
Michael Williams, suspect in the 24th street homicide, is in police custody thanks to a citizen tip. He was located in the Sacramento area.— Sacramento Police (@SacPolice) July 29, 2014
"He's a local kid. He has a following here in Sacramento. And having his name attached with us and helping in this investigation will help us actually solve this matter," Somers told ABC News.
Thank you guys for your support & tips that brought a murder to justice. Love y'all!— Matt Barnes (@Matt_Barnes22) July 29, 2014
I stand here 2day calling out #ALLAthletes&Entertainers who have this "platform" those of us who have a voice & resources 2 get things-cont— Matt Barnes (@Matt_Barnes22) July 29, 2014