SAVAGE, Minn. (AP) - A woman who went to inquire about a nanny job advertised online was found dead in the trunk of her car, police said.

The body of Katherine Ann Olson, 24, was found in her car at a Burnsville park late Friday, Police Capt. David Muelken said. She was last seen by friends Thursday morning, when she went to meet someone in Savage about a nanny job. Investigators said she had found the ad on the Internet bulletin board Craigslist.org.

A 19-year-old Savage man who police believe placed the ad was being held pending charges, police said. Authorities did not release his name but said charges could be filed as soon as Sunday.

"We're confident we have the suspect in custody," Muelken said.

Muelken declined to say how Olson was killed or what the motive may have been.

A Savage resident found Olson's purse in a garbage can at Pacer Park. A police officer, thinking it may have been stolen, left a message at Olson's home saying police had the purse, Muelken said. Olson's roommate called back to say Olson hadn't been seen since 8 a.m. Thursday when she went to interview for the job.

Rechecking the garbage can, police found a bag containing a bloody towel, Muelken said. A State Patrol helicopter pilot noticed a car in the parking lot of Rudy Kraemer Nature Preserve in Burnsville, a few blocks from Pacer Park. Police identified the car as Olson's, and found her body in the trunk, he said.

Olson was a 2002 graduate of Park-Cottage Grove High School, where she was co-valedictorian, and from St. Olaf College in 2006.

Olson's family told the newspaper she had taken nanny jobs at least twice before, including a job in Turkey, after answering online ads.