A surprise birthday party for Dawn Wells, the actress who played Mary Ann on "Gilligan's Island," ended with a nearly three-hour tour of the Teton County Sheriff's Office and jail when the 69-year-old was caught with marijuana in her vehicle while driving home.

Wells is now serving six months' unsupervised probation for the crime. She was sentenced Feb. 29 to five days in jail, fined $410.50 and placed on probation after pleading guilty to one count of reckless driving.

The guilty plea came as part of an agreement with prosecutors in which three misdemeanor counts -- driving under the influence, possession of drug paraphernalia and possession of a controlled substance -- were dropped.

The case began the night of Oct. 18, when Teton County Sheriff's Deputy Joseph Gutierrez arrested Wells as she was driving home from a surprise birthday party. She posted $4,000 bond and was arraigned on the charges the following day, pleading not guilty. A trial on the matter was scheduled for March 13, but was canceled because of the plea agreement.

According to the sheriff's office report, Gutierrez pulled Wells over after noticing her swerve across the fog lines and center lines of State Highway 33 and repeatedly speed up and slow down.

"I exited my patrol vehicle and immediately was able to smell a strong odor of burning marijuana," Gutierrez wrote in his report. "As I approached the vehicle I noticed all four window (sic) of the vehicle were lowered and the female driver was not wearing a jacket."

When Gutierrez asked why he could smell marijuana, Wells reportedly told him that she'd just given a ride to three hitchhikers and had dropped them off when they began smoking something. When Gutierrez searched the car, he found three half-smoked joints in the ashtray and console, according to the report. A second search after Wells' arrest netted a fourth half-smoked joint and two small cases used to store marijuana, Gutierrez said.

After Wells failed a field sobriety test, she was handcuffed and taken to the sheriff's office.

Wells' attorney, Ron Swafford, of Idaho Falls, told the Post Register that a friend of Wells' voluntarily testified that he'd left a small amount of marijuana in the vehicle after having used the vehicle that day, and that Wells was unaware of it.

Swafford said several witnesses were prepared to testify that Wells had very little to drink at the party and was not intoxicated when she left. He said she was swerving on the road because she was trying to find the heater controls in her new car.