Reward In Missing Couple Murder Mystery

Thursday is the fourth anniversary of the disappearance of a couple last seen at a Philadelphia nightclub.

Authorities are once again seeking the public's help in finding out what happened to Danielle Imbo and Richard Petrone Jr.

Slideshow: Images Of Missing Couple

Imbo and Petrone had known each other since high school and had recently started dating at the time of their Feb. 19, 2005, disappearance. That Saturday night, they were at a club on South Street when they told friends they planned to return to Imbo's home in Mount Laurel, N.J., in Petrone's pickup truck.

Imbo, Petrone and his truck haven't been seen since. The FBI says Imbo and Petrone might be victims of a murder-for-hire scheme.

Only On Fox: Father Of Missing Man Speaks Out

Everyday is painful for Rich Petrone and his family. Four years after his son, Richard Jr., and his girlfriend, Danielle Imbo, disappeared, there are daily reminders of the immense loss.

"There's never a good time, some are much worse than others," said Richard Petrone in an exclusive interview with Fox 29's Dave Schratwieser.

Last February, the FBI announced the couple's disappearance from a South Street bar was a murder-for-hire plot, carried out by yet unknown killers. The young couple's bodies and their pickup truck have never been found.

"We're optimistic that we're gonna solve this case. We're still following up on the leads that we have, aggressively pursuing it and we're not giving up on it," said FBI spokesman J.J. Klaver.

FBI agents and detectives have scoured the area for the bodies, digging up garbage dumps and empty lots. Divers have searched lakes and waterways in vain.

"The thought that your son is laying out there somewhere, God knows where, in a marsh, in a field, in a trash dump," said Petrone.

Petrone believes more than one person carried out the hit. "Sooner or later, people talk. This was not a one-man operation. It took more than one person to make two people and a truck disappear."

While the investigation remains active, the sadness never leaves. Petrone runs the family bakery everyday, remembering the good times with his son at his side.

The Citizens Crime Commission is offering a $50,000 reward for information that leads to the victims' whereabouts.

"It’s important forensically. It's important to the families to put this to rest for them. But any piece of information is important in helping us solve this," said Klaver.

"It would be important to know that whoever did this, pay for it," said Petrone.

If you have any information in this case, you're asked to call the Citizens Crime Commission at 215-546-TIPS. You can give your information anonymously. It could help ease the pain for the Petrones and the family of Danielle Imbo.