Updated

The search for a missing 38-year-old Oregon mother has expanded to the San Juan Islands off the coast of Washington state and some 300 miles from where she was last seen.

Jennifer Huston, of Dundee, Ore., was captured on security footage July 24 at a gas station in nearby Newberg after leaving her home to run errands. Huston, a stay-at-home mom with two small children, has not been seen or heard from since.

Authorities have now broadened their search to include the San Juan Islands, where Huston, originally from Washington state, enjoyed visiting with her family. The area is approximately 300 miles north of the Portland suburb where Huston lives.

Detectives with the Newberg-Dundee Police Department told FoxNews.com that Huston's vehicle, a 1999 dark green Lexus LX 470 SUV, would be able to travel 300 to 350 miles on a full tank of gas.

Capt. Tim Svenson of the Yamhill County Sheriff’s Department asked a friend and colleague in San Juan County, Wash., to issue a bulletin.

"We’re trying to cover all of our bases," Svenson told Fox News. "Jennifer graduated from Gig Harbor High School and used to vacation on the San Juan Islands."

The Washington State Ferry system is cooperating as well. They're looking at security video to see if her vehicle took a ferry to the Islands.

Huston was last seen on surveillance video leaving a Circle K gas station in Newberg at approximately 6:22 p.m. Minutes later, her cellphone shut off. Police said it was not due to a dead battery.

Huston spent about $40 on gas -- leaving her with a full tank, according to authorities. She had left her home just before 6 p.m. to run errands, her husband, Kallen Huston, told police. He said she was complaining of a headache.

Detectives learned that Huston withdrew a small sum of cash from the Oregon First Community Credit Union in Newberg and then purchased gas with her debit card. From there, she visited a Rite Aid pharmacy where she bought Gatorade, trail mix, and non-lethal sleeping pills. There has been no activity since on Huston's bank cards.

Cpt. Jeff Kosmicki of the Newberg-Dundee Police Department said the last cellphone tower the phone pinged from was north of the gas station but "more technical" data is needed, like "latitude and longitude" information that might show which direction she was headed in.

Detectives, however, have hit a roadblock in obtaining such information because they cannot prove a crime has been committed. Kosmicki said authorities would also like access to Huston's medical records but are forbidden from obtaining them due to the federal HIPAA law.

"It's impossible," Kosmicki said.

He also noted that detectives viewed security footage of Huston withdrawing money from an ATM, but said they cannot physically obtain the video because of lack of proof a crime has been committed. The video is valuable, Kosmicki said, because it provides the clearest images of Huston on the day she disappeared and could help solve the case if released to the public.

"We aren't able to have that video in our hands from the bank," he said.

Multiple searches have been conducted by air and land for any sign of Huston and her vehicle. A family friend donated a helicopter to fly over the 750 square mile county. Fixed wing planes, including crop dusters, have also been involved in aerial searches of Yamhill County. So far the efforts have been futile.

Huston's husband, who passed a polygraph test, said his wife had complained of a headache for "several days" prior to her disappearance. He said the headache was not serious enough to warrant a doctor’s visit, but he did tell investigators his wife seemed a little stressed out when she left the house. He assumed she just needed a quick break, normal for any stay at home mom.

Kallen Huston said earlier this week that his wife might have driven off the road and urged motorists to look for any signs of his wife and her vehicle.

"I have a feeling maybe she's in a ditch somewhere," he said during a press conference. "We've exercised every option that we can think of right now."

Meantime, Huston’s babysitters told KGW-TV in Portland that they were booked to watch Jennifer’s boys so she and her husband, Kallen, could celebrate their 10-year wedding anniversary. Morgan and Amanda describe Huston as a very involved and dedicated mom.

"We just don’t get it," Amanda told KGW, "She would never leave her kids."

A Facebook page set up in the search for Huston says she was last seen wearing black and pink Nike shoes and black yoga pants. Her vehicle, a 1999 Lexus LX 470, has an Oregon license plate of WXH 011.

Anyone with information is urged to call the Newberg-Dundee Police Department at 503-538-8321.