It happened at the Bernard Grocery Store on North 27th Street in Cam back in December, 2011. Three armed robbers opened fire in the store, killing owner Miguel Almonte as he begged for his life.
The suspects took cash and got away.
On Thursday, police were in the area handing out flyers to spread the word.
"Prayfully we're hoping that citizens will step up," said Camden Mayor Dana Redd.
The $21,000 reward is the biggest in Camden's history, but Camden County Police Chief Scott Thomson said there is a reason for it.
"An individual walked in with a military-style assault rifle. This is not a shoot-out with rival gangs in which somebody died. This is an individual that, through our investigation, had no involvement in criminal activity," Chief Thomson said.
Almonte's brother, visiting from the Dominican Republic, thanks law enforcement for their efforts, as did neighbors who knew the victim.
"He was a nice guy. If you were short he'd say 'No problem,' if you need something to eat, 'No problem.' He was that kind of person," said Jose Santiago.
Anyone with information is urged to contact Camden County police at 856-757-7400.