MIAMI -- Gus Boulis was a true rags to riches story. He was an immigrant who came to South Florida and went on to build a financial empire. He lived a fast-paced life that ended in murder.

It's been four years since Boulis was gunned down in his car in Fort Lauderdale, in what looked like a planned hit. There were precious few clues to work with to solve the case, but Local 10's Rad Berky found out that Fort Lauderdale detectives believe they are now very close.

Detective Art Carbo is still trying to solve the Boulis murder -- what was his first homicide case, and he says he has not given up an ounce of hope.

"We're so very close and have been so very close for a long time," Carbo said.

Four years after the founder of Miami Subs and the one-time owner of the Sun Cruz Casino empire was gunned down, detectives think they have been on the right track from the beginning in looking for Boulis' killers.

"His troubles begin with the sale and purchase of Sun Cruz Casinos," Carbo said.

Boulis sold Sun Cruz to Adam Kidan, but it was a contentious sale that left the two men at odds with each other.

Carbo zeroed in on a mysterious series of checks totaling $105,000 from Kidan payable to a Miami Beach company called "Moon Over Miami."

The man behind Moon Over Miami is a self-described cousin of mobster John Gotti whose name is Anthony Ferrari.

Carbo wanted to ask Ferrari about the checks from Kidan and what Ferrari's company had done to earn the money, but Ferrari wasn't talking.

"He (Ferrari) was someone who made himself unavailable to us immediately, probably within days of the homicide," Carbo said.

One of the only leads police had was a sketch of the suspected gunman who a witness said was driving a black Ford Mustang when he pulled up alongside Boulis and shot him. So investigators were intrigued with a man named James Fiorillo, an associate of Ferrari -- not because Fiorillo looked at all like the sketch, but because of the car Fiorillo was driving at the time of the murder.

"He drove a black mustang that vanished," Carbo said.

Berky asked, "Right after the murder?"

"Apparently so," Carbo answered.

That could be nothing more then coincidence, but investigators say they believe they are on the right track and that one day, someone is going to talk.

"In this case we have a pretty good handle on what we believe happened but knowing it and proving it are two different things," Carbo said.

Every year around the time of the anniversary of Boulis' death, someone leaves flowers where his car came to rest -- but no one knows who it is. It's just another of the enduring mysteries that surrounds this case.