A discarded cigarette butt proved to be the pivotal piece of evidence investigators needed to tie a suspect to a 2012 homicide outside a popular Pennsylvania diner, police said.

Vallis L. Slaughter, 39, was arrested last week at his mother's home in New Jersey, about a month after investigators obtained DNA from the smoldering cigarette and compared it to a Styrofoam cup collected at the scene of the fatal shooting 12 years ago, authorities announced Monday. Slaughter, who was set to be extradited to Pennsylvania for his first court appearance, has been charged with murder, aggravated assault and conspiracy, said Berks County District Attorney John T. Adams at a news conference.

The charges stem from the 2012 fatal shooting of 34-year-old Julio Torres in the parking lot of a diner in West Reading, a borough of Berks County located about 60 miles northwest of Philadelphia.

Though authorities were quick to identify and arrest an accomplice in the shooting, the cold case had lingered unsolved for more than a decade when authorities failed to determine the suspect who pulled the trigger.

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Styrofoam cups linked to assailants collected in diner parking lot

Torres was shot and killed March 24, 2012 while seated inside his vehicle in the parking lot of the diner, the district attorney's office said in a news release.

When the identity of the suspects eluded authorities for months, the West Reading Police Department formed a joint task force in May that year with the district attorney's office.

Investigators examined surveillance footage that showed Torres arguing in the parking lot with two men before one of them pulled out a gun and shot him to death, Adams told reporters. Nothing in the investigation indicated that Torres knew either of his assailants.

"To date we have never determined what the motive was for this shooting other than some senseless dispute," Adams told reporters Monday.

The surveillance footage also revealed that both suspects were holding foam cups prior to the shooting, Adams said. Investigators were able to collect the cups, along with a bitten off piece, from the parking lot and send them to the Pennsylvania State Police's forensic crime lab for DNA analysis.

A DNA profile developed from one of the cups led to the arrest of 22-year-old Jomaine Case, who was eventually convicted for his role in the fatal confrontation, Adams said. But a profile developed from the other cup and bitten-off piece did not match any existing DNA in databases across the United States, including the Combined DNA Index System (CODIS,) a database of convicted offenders used by law enforcement.

Authorities determined that the gunman was likely a man visiting West Reading from New York, but with no leads to go on, the investigation sputtered out.

"The person responsible for pulling the trigger and shooting Julio Torres was never, never identified," Adams said Monday.

DNA from cigarette butt links Slaughter to 2012 shooting

The cold case languished for years until detectives decided to review it again in 2023.

A break came when investigators uncovered a cell phone photo from 2012 that they believed showed the suspected shooter at a party hours before the homicide took place. Facial recognition software helped them identify the suspect in November as Slaughter, who is originally from Brooklyn, Adams said.

Slaughter was tracked in December to Jersey City, where investigators determined he was living with his mother. Detectives surveilled the home for weeks until on Feb. 9, they witnessed Slaughter discarding a cigarette butt onto the sidewalk before entering the residence, Adams said.

Detectives collected the cigarette and sent it back to the Pennsylvania forensics lab for analysis. Earlier this month, their suspicions were confirmed when the crime lab notified the investigators that DNA from the filter of the cigarette matched what was obtained from the second foam cup in 2012, according to the district attorney's office.

Slaughter, who Adams said is also a suspect in a homicide in Brooklyn, was arrested March 20 by Jersey City police at his mother's home.

"Just having that DNA sample isn't enough, but we were able to utilize technology to identify this individual and now we have confirmed that identification with DNA," Adams told reporters. "We are not going to give up, and if we can continue to pursue justice for the victim, we will do so."

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]