The cell phone and car of a woman who has been missing since Saturday were found more than 130 miles south of the conference where she was supposed to be.

Demi Helenius, 23, was attending a Landmark Worldwide Forum self-improvement conference at the Embassy Suites Hotel in Portland, Oregon, on Saturday.

When the conference took a dinner break at 6pm, police say she did not return, KGW.com reported.

Once the conference was over for the night, she did not return to Rock Creek where she lives with her parents. She didn't call or text them where she was, which her family says is unusual.

The Washington County Sheriff's Office is investigating her 'strange' disappearance, but they say there are no signs of foul play at this time.

Demi Helenius, 23, (pictured) has been missing since she disappeared from a Landmark Worldwide Forum self-improvement conferencein Portland, Oregon, Saturday

When the conference took a dinner break at 6pm, police say Helenius did not return. Once the conference was over for the night, she did not return to Rock Creek where she lives with her parents. She didn't call or text them where she was, which her family says is unusual

'It is very out of sorts that she would leave and not contact us,' her mother Melody Helenius told KGW.

'She does live at home. She's going to college, she writes music, she's a half-marathon-er and she is full of life and this is not her character.'

The Washington County Sheriff's Office is investigating Helenius's (pictured) 'strange' disappearance, but they say there are no signs of foul play at this time

When her family didn't hear from Helenius, her brother decided to call her.

Instead of his sister on the other end of the line, an employee at a Dairy Queen in Creswell, Oregon, answered the phone. Creswell is 130 miles south of where the Portland conference was.

The employee said a man who went through the drive-thru turned in the phone when he found it in the parking lot.

Police have since spoken to the man who said he found the cell after he saw someone throw it from a car, Oregon Live reported.

On Monday, Helenius's car, a black 2013 Volkswagen Bug, was found in Cottage Grove, about 10 miles south of the Dairy Queen where her phone was found.

Investigators say there were no signs of foul play after an initial examination of the car. However, it will be processed more thoroughly.

Her cell phone was found in a Dairy Queen parking lot a few hours after she went missing from the conference in Portland (top). The Dairy Queen is about 130 miles south of the conference in Creswell, Oregon (center). Her car was found Monday 10 miles south of the Dairy Queen in Cottage Grove (bottom)

On Monday, Helenius's car, a black 2013 Volkswagen Bug, (pictured) was found in Cottage Grove, about 10 miles south of the Dairy Queen where her phone was found. Investigators say there were no signs of foul play after an initial examination of the car

Police said they have also spoken with a man who attended the same conference, but did not check back in after the dinner break Saturday night, according to KGW.

Officials have not named any suspects in their investigation.

Landmark Worldwide Forum gave a statement saying: 'We have been in communication with the Washington County Sheriff’s Office to give them all the information we have to support them in their efforts to locate Demi.

'Our thoughts and concerns are with Demi and her family and like her family, we hope she is safe and found quickly.'

Helenius has still not been in contact with her family.

Anyone who has seen Helenius is asked to call police at 503-846-2500.

Demi's mother Melody Helenius said: 'It is very out of sorts that she would leave and not contact us. She does live at home. She's going to college, she writes music, she's a half-marathon-er and she is full of life and this is not her character'