Katherine Ann Olson, 24, was found dead in the trunk of her car at a Burnsville, Minnesota, park late Friday night. She was last seen by friends Thursday morning, when she went to meet someone in Savage about the job, which investigators said she had found on Craigslist.org, a popular Internet bulletin board.
A 19-year-old man from Savage who police believe placed the ad is being held in the Scott County jail pending charges expected to be filed Tuesday. He worked at Minneapolis-St. Paul International Airport, where police arrested him Friday night.
The suspect, identified as Michael John Anderson, was scheduled to appear in court Tuesday, reported CBS News correspondent Dean Reynolds.
"We're confident we have the suspect in custody," Police Capt. David Muelken said.
A spokesman for Craigslist told Reynolds that, if the link to the site is confirmed, it would be the first muder ever tied to Craigslist in its 12 years of existence.
"Investigators are working with Craigslist," Muelken told Early Show co-anchor Harry Smith, "and they have been cooperative."
In a KMSP-TV interview, the victim's father, Rolf Olson, says the family is devastated but "there was some sense of peace that they found her."
Olson was a 2002 graduate of Park-Cottage Grove High School, where she was co-valedictorian, and from St. Olaf College in 2006.
Her family said had taken nanny jobs at least twice before, including a job in Turkey, after answering online ads. They said they had misgivings about her finding jobs online, but she never seemed to worry.
That last help wanted posting, said her sister, Sarah Richter, "seemed kind of fishy, but she was just going to check it out, and meet them."
Olson's family gathered in front of their home Saturday afternoon to share stories of a vivacious young woman "who was a joy, who trusted people" and always assumed the best in others. They said they were finding strength in the people who were touched by Olson's life.
"She was going to set the world on fire, and that's the grief that we feel," said her mother, Nancy Olson. "It's not just for us, it's for all these other people that she would have touched."
Citing the ongoing investigation, police were cautious about the details they released. They declined to say how Katherine Olson might have been killed or whether a weapon was used. They said they weren't sure of a motive.
Muelken said a resident told a Savage Public Works employee about a purse found in a garbage can at Pacer Park. A police officer retrieved the purse, which contained belongings of Olson's. Thinking it was a theft, police called Olson's home and left a message telling her they had her purse. About 5 p.m. Friday, Olson's roommate returned the call and told police Olson hadn't been seen since 8 a.m. Thursday, when she went off to Savage to interview for a baby-sitting job.
Police went back to the park and found a garbage bag in the container. Inside it was a "significantly bloody towel." An extensive search of the area ensued. A State Patrol helicopter pilot noticed a car in the parking lot of Rudy Kraemer Nature Preserve in Burnsville, a few blocks away from Pacer Park. Police identified the car as Olson's, and found her body in the trunk.