According to the AP:

A woman advertised on the popular Internet site Craigslist for an assassin to kill the wife of a man with whom she'd had an affair, authorities said Saturday.

The ad by Ann Marie Linscott, 49, was posted in November as a generic request for somebody to perform a "freelance" job, court document said. Her true intention was only communicated to those who e-mailed her seeking additional information about the job, the Craigslist CEO said.

Linscott offered $5,000 for the hit, had the name and work address of the woman she wanted dead and she described successful candidates as "silent assassins," according to agents and court documents.

According to WZZM:

After her arrest at her Rockford home, Linscott gave chilling responses to the FBI's questions outlined in the Federal Criminal Complaint.

When asked what she meant by "eradicating" the victim she said
"Duh. Well to have her killed."

When asked how she would feel if the victim was in fact murdered, she said she feared law enforcement would "track the murder back to her."