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An Oregon woman detained for months in East Timor has been released from prison.

Stacey Addison, 41, of Portland was arrested in September after crossing the border into the small Southeast Asia nation. The veterinarian was sharing a taxi with a man who asked the driver to stop the car at a DHL office so he could pick up a package. Police stopped the vehicle and found methamphetamine in it prompting the arrest.

When she was released on Sept. 9, authorities said their investigation was continuing, and Addison, who has no criminal record, was eager to cooperate. Her urine test came back negative for drugs, and her computer records were clean. She was granted "conditional release," meaning she could travel freely throughout East Timor, but could not get her passport back. She hired a lawyer and soon learned that such investigations could take up to a year.

"I am overjoyed to learn of Dr. Stacey Addison's release from prison," said U.S. Sen. Jeff Merkley, D-Ore., who has been working to secure Addison's release. "This is wonderful Christmas news."

Addison's mother, Bernadette Kero of Klamath Falls, Oregon, said in a phone interview she is "tremendously relieved," and will be even more so when her daughter gets her passport returned. For now, Addison is staying at the guest house of former President Jose Ramos-Horta.

Kero said she spoke with Stacey twice on Christmas Eve, and her daughter, though obviously happy, was still in some disbelief over the whole situation.

"I anticipated it not being a very good Christmas," Kero said. "And this is just the best Christmas present, other than her actually coming home."

Addison's visit to East Timor was to be a highlight of a series of trips around the world. A graduate of University of California-Berkeley and UC Davis, she lived frugally, and sold her car and most of her possessions ahead of her trip. She looked forward to seeing the area's exotic animals and meeting doctors in the same line of work. She had already been to Antarctica and parts of Europe. After a brief visit home, Addison resumed her trip in March.

With the help of her friends, Addison was able to give updates about her condition in the country. Addison admitted she was lonely and frightened and described her stay as a nightmare.

Fox News' Claudia Cowan and the Associated Press contributed to this report