POST FALLS, Idaho -

The Post Falls Police Department and Kootenai County Sheriff's Office are searching for a missing woman whose unoccupied car was found by an officer at Q'emiln Park overnight.

According to police, Joan Gundlach, 70, was last seen leaving her home around 10 a.m. Tuesday. While completing a routine check of Q'emiln Park, an officer found Gundlach's car at the trailhead.

The officer ran the license plates on the car and contacted Gundlach's husband, who confirmed he knew the car was parked where the officer had found it. The man said he found a suicide note in bed Tuesday night that directed him to where Gundlach's car would be. He went out to the site, saw her car -- but no sign of her -- and then went home but never called the police.

When asked why he didn't alert authorities the man said he was "too shocked to call the police."

Police said Gundlach was depressed and possibly suicidal. Gundlach's husband said the couple had been married 30 years and that his wife had been dealing with depression off and on for years but never went to a doctor and wasn't willing to get any help. He added she last talked about committing suicide a week ago.

Authorities are investigating this as a missing persons case with suspicious circumstances. Police said there are a number of questions regarding the behavior of missing woman's husband in not reporting the suicide notes, her car's location or her disappearance and she has not been located.

Thursday morning officials said that the husband is not considered a suspect in Gundlach's disappearance; they later amended that statement when Post Falls Police Captain Pat Knight said, "I think at this point everyone is a suspect until we can prove otherwise."

Officers searched the park and Spokane River, while MedStar provided a helicopter to help search the river for signs of Gundlach. MedStar was called in to assist since the Spokane County Sheriff helicopter Air 1 was unavailable due to maintenance Thursday.

Gundlach is described as being white, about 5'8" and 155 pounds. She has brown hair and brown eyes. It's not known what she was wearing.

Anyone with information is asked to call the Post Falls Police Department at 208-773-3517.