The woman believed to be responsible for two bank robberies in Napa last month is behind bars, along with the man police say is her accomplice.

Melanie Elizabeth DePalmer, 26, and Michael Lilly Martin, 27, were arrested over the weekend by San Diego officers.

DePalmer is charged with robbing Wachovia Bank on Trancas Street in north Napa on Oct. 17. She approached a teller, demanded money and said she was armed. No weapon was seen.

Eight days later, police say, DePalmer walked into Bank of America on Trancas Street and Big Ranch Road and showed a teller her checkbook, where a note was written demanding money. The robber did not make any mention of being armed.

After the Wachovia bank heist, the robber dropped the note she showed the bank teller. Investigators were able to identify DePalmer from fingerprints on the note, Napa Police Cmdr. Andy Lewis said.

Her photograph, taken by the Wachovia Bank surveillance camera at the time of the robbery, matched the photo taken of the robber by the Bank of America surveillance camera, Lewis said.

At that point, investigators were able to obtain an arrest warrant for DePalmer, he said.

Meanwhile, Martin was previously identified by Santa Rosa Police as the suspect in the Wells Fargo Bank robbery there on Oct. 15.

Flyers for information about his whereabouts were distributed to law enforcement agencies throughout the state.

Lewis said DePalmer and Martin, who live in El Cajon, near San Diego, were gambling at a casino in El Cajon over the weekend.

They obtained some bad methamphetamine and got sick, Lewis said. "They admitted themselves to a nearby hospital for treatment."

Lewis said a hospital security guard, who is also a San Diego County police officer, recognized Martin from the flyers.

Authorities were called to the hospital. Martin and DePalmer were arrested and charged with bank robbery.

The red Ford Focus used in the Bank of America robbery in Napa was also recovered. Authorities also obtained warrants to search the couple's belongings. Lewis said the couple had rented a room at the casino where they were gambling.

Lewis said when the Napa robberies occurred, Martin and DePalmer were visiting Martin's relatives in Santa Rosa.

Authorities believe DePalmer and Martin are responsible for five or more robberies in Southern California, Napa Police Cmdr. Andy Lewis said. The FBI is assisting in the investigation.

As of Monday afternoon, DePalmer and Martin were still in custody in San Diego County.

"We are working with the federal authorities to work out who will be prosecuting the case," Lewis said.