The drug-fueled binge of three Bethlehem men began early Friday when they snorted a synthetic drug known as flakka, police say, and ended several days later with the bludgeoned, lifeless body of one of them stuffed in a car trunk and another charged in his death.

Police say they found the man accused of the killing, James Heimbach, in his underwear screaming at passing cars, capping a homicide investigation into what one police chief called a drug that causes "off the charts" behavior. It led officers from a blood-splattered, drug-riddled city apartment to a car in Pocono Township that had the body in the trunk.

Bethlehem police Chief Mark DiLuzio said it's the first case he knows of involving flakka, a synthetic drug that combines bath salts, LSD and amphetamine and has made headlines elsewhere with users displaying super-human strength and bizarre behavior.

Heimbach, 30, used the butt of a shotgun to bash his friend to death at Heimbach's apartment in the 900 block of East Sixth Street, according to police arrest records.

But Heimbach told investigators the man he's accused of killing, 27-year-old Joseph Goda, leaped on him, punched him, tried to bite his face and gnawed at his hands while they partied at Heimbach's South Side apartment.

Heimbach told police he was "fighting for his life," but somehow broke away and ran out the back door, court records state.

Heimbach said his next memory was three days later when Pocono Township police stopped him wearing only his underwear as he ran into traffic, yelling and delusional, according to court records.

According to arrest records, police believe Heimbach didn't flee his attacker, but bludgeoned him to death with the shotgun early Friday. Authorities say Heimbach and the third man who took flakka, Charles Anthony Yocum, 32, then wrapped Goda's body in a carpet and put it in the trunk of Yocum's mother's car.

Police said the two men planned to dump the body at the New Jersey shore, but spent several days continuing their spree fueled by flakka.

"This is the first (flakka) case I know of here and, already, it's connected to a homicide," DiLuzio said. "It's a truly terrifying drug that seems to turn users into zombies. They can't feel pain. Their behavior is off the charts."

Yocum told police he witnessed the killing and authorities said Goda was clutching a bloody T-shirt with "Team Heimbach" on it, a shirt that belonged to Heimbach.

Goda lived in Bethlehem with a friend for the past two years, said his mother, Judith Goda. She sobbed as she spoke about the circumstances surrounding his death.

"I'm just in shock," Goda said. "It's a nightmare."

Goda said she didn't know either of the men charged in her son's death. She was hopeful that police would soon give her details about the ongoing investigation.

"It's been very difficult for us," Goda said.

Authorities say they believe Goda died Friday morning in Heimbach's apartment. His body was found Monday in the car trunk, police say.

According to court records:

On Friday, an apartment manager went to meet with Heimbach about signing a new lease, police said. Heimbach didn't answer the door, and the manager went inside and found blood on the living room floor and wall.

He called police and investigators found a "substantial" amount of blood splattered across the walls and floors; so much blood, police said, that they knew someone had been severely injured, and began searching for Heimbach.

In the apartment, police said, they also found signs of drug use, including a straw and white powder on a kitchen countertop and powder scattered around an open safe containing large plastic sandwich bags and empty pill capsules. Police also found a shotgun shell on top of a mattress in the apartment's bedroom.

It wasn't until Sunday that Heimbach's mother, Paula Donham, told police that her son was being cared for at Pocono Medical Center in East Stroudsburg. Pocono Township police said they had found Heimbach running through traffic in his underwear at an intersection in Tannersville. He was charged with public drunkenness and taken to the hospital.

Police said they found a dog barking in a car parked in a grocery store lot a short distance away. Yocum was found running in nearby woods, police said. He had no shirt on and was asking people for a phone and a ride to Bethlehem.

In a Monday interview, Heimbach told police he was with Yocum and Goda at his apartment Friday when they used flakka. Police noted he had scratches on his arms and several bite marks.

Yocum told police that he saw Heimbach kill Goda with blows to the head with a shotgun that police are still searching for. He said Heimbach then rolled Goda's body in a carpet and put it in the trunk of the car with the intent of dumping the body in the ocean.

Police said on Monday, the car left in the East Stroudsburg parking lot was towed to Bethlehem, where investigators found blood on the seat and noted an "unusual" odor inside. When officers checked the trunk, they found Goda's body, according to court records.

Heimbach is charged in the killing and is in Northampton County Prison without bail. Yocum, of the 1400 block of East Sixth Street, is charged with abuse of a corpse, obstructing police, tampering with evidence and hindering an investigation. He was sent to the prison under $200,000 bail.

Jennifer Sicher, who lives next to Heimbach, said he's "very nice, very polite."

"I never really saw him much. He would say, 'Good morning,' and ask how you are doing," Sicher said.

She didn't know if he had many visitors. But he did have a Doberman pinscher, she said.

Sicher didn't know about the homicide until the police showed up at the home Monday, adding she was shocked to learn the killing happened next door.

Yocum and Heimbach have criminal histories, according to online court records.

In 2005, Yocum was charged by Bethlehem Township police with sexual assault of a victim under age 13. Yocum pleaded guilty to statutory sexual assault and indecent assault and was sentenced to prison. He also pleaded guilty to drug charges in 2003 and 2005.

In 2007, Heimbach pleaded guilty to drunken driving, possession of drugs and carrying a concealed weapon without a license. The charges were filed by Bethlehem Township police.