CHESTER In addition to the two people arrested since Saturday, Delaware County authorities suspect others may have played a role in the murder of a Chester drugstore manager shot to death last week.

"We think there may be others involved," District Attorney Jack Whelan said Tuesday.

David Wiggins, 24, and Rita Pultro, 23, both of Philadelphia - and both on probation for other crimes - were arrested last weekend and charged with murder, robbery, firearms violations, and related crimes in connection with Thursday's slaying of Jason Scott McClay, 40, a Rite Aid manager.

Asked about a possible motive, Whelan said it was "the oldest motive in the world, money," that prompted a robbery that apparently went bad.

He credited cooperation with the Philadelphia Police Department for the relatively quick arrests of the two suspects he described as both "down and out on their luck."

McClay, of Haverford, was killed 10 minutes before the store was to close.

According to police, Pultro allegedly entered the store with Wiggins. She asked McClay if the store carried motion-sensing lightbulbs. He accompanied her to the rear of the store. Witnesses said they then heard a loud bang and saw the couple run.

McClay was shot at close range and sustained wounds to his neck and chest. He was pronounced dead at 10:01 p.m., according to court records.

Police were able to identify Wiggins as a suspect through a palm print on a door. Witnesses were able to identify him from photos, according to court records.

In February 2010, Wiggins was arrested in Philadelphia for a car theft. He pleaded guilty and was sentenced to up to 23 months in jail and three years' probation. He was released in March 2011.

Since then, he has been arrested on burglary charges, sentenced to four years' probation, and ordered to undergo drug treatment. In March, a judge ordered Wiggins back into drug treatment after he violated probation.

Wiggins was arrested Saturday. When questioned by police, he allegedly said that the robbery went awry and that he wrestled with McClay. He said Pultro pulled the trigger. Whelan said investigators believe Pultro was the shooter.

Pultro, who worked as a bartender at 25 & Up, a lounge at 29th and Reed Streets in the Grays Ferry section, was working a 7 p.m.-to-2 a.m. shift that night. According to police records, she told coworkers she needed to leave for a medical situation concerning her 7-month-old child. She returned around 10:30 p.m., witnesses told police.

Wiggins was known to frequent the bar as well, customers said.

An employee who did not want to give his name said Pultro started working there about three weeks ago and was diligent. She came to work on time, kept the establishment clean, and was well liked by the customers.

"Everything seemed to be fine, and then I seen her on TV," he said.

Pultro was arrested Sunday without incident at a residence in the 1300 block of Harrison Street. When police said they needed to look for the red jacket seen in the surveillance photos captured at the store, Pultro allegedly said, "I already got rid of the jacket and bandanna," according to court records.

When asked about the weapon used in the crime, Pultro said she didn't know where the gun was, according to court records.

"This is all a big shock to me as it is to anybody," said John Dodd, a distant relative of Pultro's by marriage. Dodd and his wife have had custody of Pultro's baby girl since the infant was one day old. Pultro gave birth to the child while in jail awaiting trial on charges of aggravated assault.

According to a police affidavit, a woman who knows Pultro said she was walking on the 3000 block of Page Street in North Philadelphia when Pultro jumped out of a truck, approached her with a razor, and repeatedly slashed at her arms and stomach. The victim was taken to Temple University Hospital and received 46 stitches.

Pultro was arrested, then ordered to electronic home monitoring, and eventually released. She is due back in court on those charges Oct. 16.

Dodd said he does not know how Pultro became involved with Wiggins. He said the incident had been "very upsetting."

George MacCartney, a salesman from Aston, also was shocked to learn of Pultro's arrest.

In July 2012, Pultro pleaded guilty to charges of stealing MacCartney's identity. She was sentenced to time served and probation. Several of the charges were dropped as part of the plea agreement, he said.

Pultro used his identity to open a Home Depot account and purchase almost $18,000 worth of goods, which she and two other accomplices later resold, MacCartney said.

"Justice wasn't done in my case," MacCartney said. "Now some innocent soul lost his life because this person was out on the street."