ATLANTIC CITY - They were staying at the Plaza, a posh, 14-story condominium complex with a pool and cabana abutting the Boardwalk at South Plaza Place.

He lived on the sixth floor. She would come and go, sometimes staying for up to three days, said Carlos Battista, who works in the valet-parking garage there.

"They were quiet," Battista said last week. "But there was something about them. . . . You knew there was trouble."

Big trouble, it appears.

Battista, who works the night shift at the garage, unwittingly played a role in the apprehension of Craig Arno and Jessica Kisby, charged last week in the carjacking-killing of casino patron Martin Caballero on May 21.

Arno, 44, and Kisby, 24, have been portrayed by some in law enforcement as a lowlife Bonnie and Clyde, based on a violent, weeklong rampage that authorities say included murder, kidnapping, carjacking, arson, robbery, and shoplifting.

But details from the investigation present a picture of the duo as a criminal variant of Hansel and Gretel, a pair of bumbling misfits who left a trail strewed with evidence.

Arno and Kisby pleaded not guilty to homicide and related charges on Wednesday in state Superior Court.

In addition to murder, carjacking, and kidnapping, charges that have them jailed on $2 million cash bail each, they have been accused in a series of crimes, including a May 26 attempt to steal a van from the Plaza garage.

The attempt, like so much else in their criminal repertoire, appears to have been neither well planned nor well executed.

By all accounts they were an odd couple at the condo complex, much younger and less polished than the typical residents of the staid high-rise far from the Boardwalk casino strip and just two blocks from the city's border with Ventnor.

Arno, released from jail in March after serving time for a probation violation related to one of several fraud convictions, was staying in a small unit that was once the residence of his mother, Gail. She now lives in Florida.

His 91-year-old grandmother, Mildred Goldman, lives in the unit next door. Neither would comment when contacted by The Inquirer.

Kisby, who has a 5-year-old daughter, lived with her mother in Egg Harbor Township. She has a conviction for aggravated assault and met Arno in February while serving time in the Atlantic County jail.

Their relationship began behind bars. By all accounts, they had known each other for four months when, authorities say, they kidnapped and killed Caballero.

Five days later, while hiding out at the Plaza, they planned their escape.

On May 26, about 5:30 p.m., Kisby asked Battista to retrieve the Toyota they customarily drove, according to the valet and investigative sources. The car, owned by Arno's grandmother, was on an upper level in the garage.

A silver Camry, it would figure prominently in the Caballero murder case.

Battista said he was bringing the car to the ground floor when he saw Kisby drive off in another resident's van, which had been parked with its key in the ignition. He jumped from the Toyota and gave chase. Around the block, he said, he saw Arno get in the vehicle.

"I yelled, 'Stop! I'm calling the police!' " he recalled.

The couple, realizing they had been spotted, apparently had second thoughts. They abandoned the van, containing two neatly packed travel bags, a few blocks away.

"We think they were planning to get out of town," said a law enforcement source, who, like several others, asked not to be identified.

Police showed Battista surveillance-camera photos of a man in a baseball cap with an "NY" insignia withdrawing $300 with Caballero's ATM card the night he was abducted.

Battista said it was Arno, "the guy from 614" - his condo number - the guy who had just tried to steal the van.

He showed police the Toyota, which he had reparked. It was the same kind of car Caballero's suspected assailants drove as they followed him into the garage at the Trump Taj Mahal Casino Resort.

Caballero, a grocery store manager from Hudson County, had gone to the Taj that night with his wife. They planned to celebrate their daughter's 22d birthday with relatives. After dropping his wife at the entrance to the casino, Caballero, 47, drove to the Taj garage.

A camera captured his Lincoln MKS entering the facility, followed by a Toyota. Minutes later, surveillance video shows a man and woman approaching Caballero, who had parked his car. A few minutes after that, a third camera recorded the Lincoln pulling out, followed by the Toyota.

Those video shots were the first of nearly a dozen over four hours to track the suspects in the Caballero case.

The victim's car was found on fire about 2:30 a.m. on May 22. It had been left in a parking lot in Gloucester Township. A law enforcement source familiar with the investigation said there were "substantial amounts of blood" in the Lincoln's trunk, leading police to believe Caballero was in it some time after his kidnapping. The body was missing, however.

Near the charred vehicle, investigators recovered a cap with an "NY" insignia, the one they believe Arno wore when he was picked up on the ATM camera.

"It looks like he got blowback when he set the car on fire," said a law enforcement source. "We've got the hat."

Investigators say they believe DNA will link the cap to Arno, calling it another piece of evidence the duo left behind.

A manager at an Exxon where Arno and Kisby allegedly bought gas to torch the car provided more incriminating details and video from the station's security cameras.

Sayeed Ali, whose station is at Route 9 and the Black Horse Pike, west of Atlantic City, told officials he sold five gallons to Kisby and a man in a Lincoln. He recognized Kisby as a former customer.

When she left the car to take the container of gas, she tried to wipe blood off the Lincoln's rear bumper, Ali said.

Kisby, he said, told him it was from a deer.

"I'm having a bad day," she said. "My car broke down. This guy [Arno] is trying to help me."

Ali said his brother, who also worked there that night, was curious about her story.

"How could a deer hit you from the trunk?" he asked.

Ali remembered one other thing about the encounter. He said the bottom of Kisby's jeans was wet and sandy.

Authorities say they believe that before they bought the gas, Arno and Kisby dumped Caballero's body. It was found May 30, badly decomposed, on the side of a sandy farm road in Hamilton Township, not far from the Exxon.

Caballero, officials said, had been stabbed repeatedly in the chest.

Investigators allege that after purchasing the gas, Kisby and Arno drove the Lincoln to where they had left the Toyota. Then, one in each car, they drove to Gloucester Township and set the Lincoln on fire.

Arno, who had burns on his hands, chest, and face at the time of his arrest, was caught in the fire's back draft, police say.

They say they believe the couple then drove the Toyota to the Plaza complex, where they remained for four days, leaving at least once to go to a Kmart in Pleasantville where Kisby allegedly shoplifted bandages and ointment to treat Arno.

They fled after a confrontation with guards at the store.

Arno, according to a law enforcement source, told his grandmother that he had been burned in a barbecue accident.

Two days after the incident at the Kmart, the couple botched the attempt to steal the van from the condo garage, investigators say.

A few hours later, they showed up on foot at the Golden Key Motel on the Black Horse Pike.

Motel owner Sunny Patel said Kisby checked in under her own name and paid $35 for one night. She and Arno moved into Room 112. The next morning, he said, she paid for a second night.

That afternoon, police arrived and arrested them.

"It was just a robbery gone bad," one police source said.

The evidence gathered in the week between Caballero's abduction and the arrests is "overwhelming," he said.

Asked why anyone would kill a stranger in what amounted to a $300 robbery, the veteran officer sighed.

"You can't look at this from a normal person's perspective," he said. "I've seen people killed for $20. It doesn't have to make sense."

Contact staff writer George Anastasia at 856-779-3846 or ganastasia@phillynews.com.