Every day, when Marge Petrone wakes up, her memory challenges her to a tug-of-war.

On better days, she'll remember her son, Richard Petrone, as a boy in his ice-hockey uniform, or as a man deftly decorating a cake in the family's bakery. She'll see his resemblance in her great-grandson's little face.

On the bad days, her memories can drag Marge Petrone toward the hole gouged out of her family's life when her son and his girlfriend, Danielle Imbo, disappeared after leaving a South Street bar.

"Every day it gets harder," she said recently. "It never gets easier."

The calendar suggests Feb. 19 might be a terrible day for the Petrones, but the Cherry Hill family says that the five-year anniversary of the couple's disappearance is simply another struggle to endure until there's a break in the case.

"It's the wait," said Marge Petrone, 61. "We have to wait. But we hope it will be worth it in the end."

On Feb. 19, 2005, Richard Petrone, 35, and Imbo, 34, were having drinks with another couple at Abilene's on Philadelphia's South Street. The couple left together shortly before midnight in Petrone's black 2001 Dodge Dakota pickup. Supposedly, they were heading back to Imbo's home in Mount Laurel.

No one has seen or heard from them since. There has been no trace of the truck.

"They vanished," said John Ottobre, Danielle's brother. "They walked out of Abilene and from the minute they got out the door, no one knows if they turned left or right. We don't even know if they made it to New Jersey."

Their credit cards, bank accounts and cell phones were never activated or used again. The Dodge Dakota was never found. If any surveillance footage was captured from the South Street area or on bridges into New Jersey, it has never been released. Investigators have followed leads in Florida and Illinois. Divers scoured murky rivers and lakes in New Jersey and Pennsylvania. Properties were dug up and landfills searched.

At each turn, there was nothing.

"To have zero evidence is amazing," said Philadelphia Police Sgt. Tim Cooney. "An entire truck disappeared."

The FBI is handling the bulk of the investigation and hasn't released any new information since 2008, when it announced that the case was being treated as a murder-for-hire.

The agency is still working on that angle, but won't say why it views the case that way.

"Most of the leads that we were previously following up on have not yielded many positive results," said Special Agent J.J. Klaver, an FBI spokesman. "The bottom line is, there is a person or persons who have knowledge of this."

Initial media reports said that Imbo's estranged husband, Joseph Imbo, allegedly had words with Richard Petrone before the disappearance. Joseph Imbo was questioned by police, but not charged. He is now living in North Carolina with the son he had with Danielle. He could not be reached for comment.

Ottobre, Danielle's brother, said his family does not see much of Joseph Imbo, other than when he brings Danielle's 6-year-old son, Joseph Imbo III, to South Jersey for visits. He said they don't talk much with the Petrones, either.

"We just knew Danielle was innocent in whatever happened," Ottobre said.

Marge Petrone does not believe her son was the intended target, either, if there was foul play.

"Richard was in the wrong place at the wrong time," she said.

Ottobre believes that reward money, a guilty conscience or an accomplice who's in a jam and looking to barter details about the incident for a lesser sentence could all play a part in breaking the case.

In August, the Petrones celebrated what would have been Richard's 40th birthday with a barbecue at his sister's house in Cherry Hill. Friends came to tell stories about their son. They listened to Bruce Springsteen, his favorite musician.

"You could feel the caring and the love and the brotherhood," Petrone said.

Some of the rituals of mourning have been denied them, though.

They have no body to bury, no accident site to turn into a memorial, no hospital to drive past with sad memories. The couple tried going to support groups for people whose children have died violently, but found themselves dancing around the edges since everyone there knew what had happened to their children. They didn't.

"We've talked about it: an illness, an accident, a war . . . but to just walk out the door on a normal Saturday night and not leave a trace, it's too hard to comprehend," Petrone said. "It's so, so over the top that there are days when you question, 'Is this real?' You just have to suspend all rational thought. Did this really happen to us?"