A former couple face hearings next month on charges they broke into eight homes during a 2009 burglary spree in central and northern Butler County.

Robert J. Duffield, 31, of Prospect and Nicole E. Brown, 29, of Clay Township each were arraigned last week on 64 criminal counts in the case.

Investigators believe drugs were the motive behind the four-year-old crimes.

“They were using these burglaries to fund their heroin addiction,” state police Sgt. Patrick Sarnese said of the defendants.

He credited police perseverance in solving the case.

The defendants — boyfriend and girlfriend living in Washington Township at the time — apparently at random targeted the homes, which were burglarized in a similar manner, police said.

The pair would drive around in Brown’s car and pick a house. They would park in the driveway and knock on the door first to see if anyone was home.

If no one was there, according to court documents, Duffield would force his way in or use a credit card to defeat the lock.

Primary on their wish lists were televisions, jewelry, guns and money.

Sometimes Duffield and Brown pawned the stolen property to get money to buy drugs, Sarnese said. Other times they would make a direct trade — stolen items for heroin.

In all, they are accused of making off with more than $7,000 in loot, documents said.

The defendants are charged with these home burglaries in 2009:

• Nov. 8 — 200 block of Calico Road, Washington Township

• Nov. 24 — 200 block of Eagle Mill Road, Connoquenessing Township

• Nov. 25 — 1800 block of Branchton Road, Washington Township

• Nov. 29 or 30 — 1100 block of Annisville Road, Washington Township

• Nov. 30 — 100 block of Pisor Road, Venango Township

• Dec. 3 — 200 block of Basswood Road, Fairview Road

• Dec. 8 — 200 block of Mahood Road, Center Township

• Dec. 13 — 900 block of Hooker Road in Concord Township.

Both suspects are charged with eight counts each of burglary, trespass, theft and receiving stolen property, as well as conspiracy to commit each of those four crimes.

Brown, who was already in the Butler County Prison awaiting trial on unrelated felony shoplifting and other charges, was arraigned Dec. 9.

Duffield was arraigned Dec. 8. He is free on $50,000 bail.

Preliminary hearings for the defendants are set Jan. 7 at the office of District Judge Lewis Stoughton in Chicora.

Meanwhile, Sarnese said the pair remain suspects in other unsolved burglaries in 2009 in “the Center Township area.”