A Niles, Ohio, woman has been arrested on charges she conspired with her then-boyfriend to rob the Hermitage branch of Citizen’s Bank on Dec. 8, federal and local law enforcement officials said Thursday.

Hermitage Police Chief Patrick B. McElhinny said Deatra A. Cayson, 33, of Niles, Ohio, was in Trumbull County Jail Thursday awaiting extradition to Pennsylvania. U.S. marshals arrested Ms. Cayson Wednesday in Warren, Ohio.

Hermitage police charged Ms. Cayson in September with two counts of conspiracy to commit robbery for allegedly writing the demand note used by Rodney J. Stefek in the robbery and driving the getaway car.

Police, who worked in concert with the FBI, which led the probe of the bank robbery, said they got a tip that Ms. Cayson had helped Stefek, 44, formerly of Niles, Ohio. Stefek confirmed the information and agreed to testify against her, police said.

The marshal’s Northern Ohio Violent Fugitive Task Force learned that she had been traveling across the country with a trucker from Warren. Law enforcement officials staked out the trucker’s mother’s home in Warren and arrested Ms. Cayson when she showed up, police said.

Stefek is serving a sentence of 12 years, 7 months in Butner, N.C. He pleaded guilty in May to a charge of bank robbery, and is appealing his sentence, which was boosted because he was deemed a career offender.

Ms. Cayson aided police in the initial investigation by identifying Stefek from a bank surveillance photo, but denied then and in a later interview that she was involved in the robbery. She told police in the second interview that she knew Stefek had ’given her up,’ police said.

Police said federal charges could be filed against Ms. Cayson, but a deputy marshal said no federal charges as of yet have been filed.