A FDLE spokeswoman, Gretl Plessinger, declined to give specifics about the case. "We do have an active investigation that started last Friday," she said.
The Florida Department of Children and Families did not respond to a request for comment on Monday. Craigslist also did not return a request for comment from the Miami Herald.
FDLE agents interviewed one woman they suspected might have behind the post, the Herald has learned; she denied any involvement. Investigators are now waiting on computer records that might help them identify the poster.
It's unclear what, if any, Florida law might be broken by posting an online ad trying to sell a child.
At least one South Florida mom has been arrested in the past decade for trying to sell her infant, but it wasn't via an online post.
Seven years ago, Kenia Quiala Bosque, of Opa-locka, was arrested after agents said she arranged to sell her 8-month-old son to a Monroe County man. She was charged with a felony charge of an adoption violation, which prohibits "to sell or surrender, or to arrange for the sale or surrender of, a minor to another person for money or anything of value."
Bosque wound up convicted and serving 180 days in jail, and she lost custody of her children.
» FROM 2017: Tenn. couple arrested for allegedly attempting to sell baby on Craigslist
Craigslist, usually used for hawking everything from rental apartments, cars and furniture, has been pilloried in the past for allowing "escort" and "dating" posts, which critics say emboldens the trafficking of underage victims. The site has since stopped running the ads.
But cases involving the trade of newborn babies are rare.
In 2017, a Tennessee man and woman were arrested after police said they tried to sell their 5-month-old son on Craigslist. Police arranged an undercover sting, and charged them with aggravated child abuse, child neglect and endangerment.
The same year, a Colorado man apologized for offering his baby for sale for $2,500. He called it a dumb joke. "Healthy white baby for sale cheap. Works fine but leaks out of his eyes occasionally," the ad read.
Four years ago, a Georgia woman was arrested after posting an ad on Craiglist asking for an unwanted baby _ so she could give the child to her 14-year-old daughter.