It doesn't have anything to do with the Death Rows where people await execution, and everything to do with Death Row Records. Basically, a Death Row chain is a piece of bling. It's a neck chain with a pendant in the shape of the Death Row Records logo. Apparently all the rappers on Death Row Records had them. What makes it notorious is someone tried to steal Tupac's from him shortly before Tupac was murdered.
'John Payne' is Death Row's current president and answering the question: A woman named 'Susan Berg' apparently bought the label back in 2008. She paid 24 million dollars for it, but that ownership didn't seem to go on for much longer: in 2009, WIDEawake-Deathrow Entertainment LLC became, and it's still, the holder the Death Row assets. Hope it helped!