Craigslist has until May 15 to eliminate its "erotic services" section for South Carolina's portion of the online classifieds or face prosecution.

The online marketplace has come under legal pressure from the attorneys general of several states to remove some of its adult-oriented sections, in part as a response to a murder investigation in Boston.

South Carolina Attorney General Henry McMaster said this week that he would begin a criminal investigation if the section isn't removed. He sent a letter to Craigslist Tuesday, saying that the Web site hasn't taken sufficient steps to prevent illegal activity and meet a November agreement with 43 attorneys general and the National Center for Missing and Exploited Children.

"Recent national events, along with ongoing law enforcement efforts in South Carolina, clearly indicate that Craigslist has not put in place sufficient safeguards in the last six months to prohibit the Internet site from being used as a vehicle to advertise or solicit prostitution and to post graphic pornographic pictures accessible to minors," McMaster's office said in a statement released Tuesday.

At the same time, Craigslist representatives met with attorneys general of Connecticut, Illinois, and Missouri.

Illinois Attorney General Lisa Madigan ordered the Web site to shut down its erotic services section last week. Missouri Attorney General Chris Koster said the site has been irresponsible in allowing prostitution ads, and he ordered the site to remove ads for illegal activities. Connecticut Attorney General Richard Blumenthal proposed several changes to the site to prevent illegal activity in that section.

Some of the backlash is fueled by a criminal investigation in Massachusetts, where an accused suspect may have used Craigslist to meet his victim. Phillip Markoff was recently charged with several felonies in connection with the shooting death of New Yorker Julissa Brisman. Prosecutors said Markoff met Brisman at a Boston hotel and tried to rob her after responding to her massage advertisement.

Craigslist responded in a blog post, saying that the "shared concerns can be addressed while preserving the beneficial aspects of Craigslist enjoyed by tens of millions of law-abiding Americans each month, without compromising the quintessentially American values of free speech embodied in our Constitution."

"We see no legal basis whatsoever for filing a lawsuit against Craigslist or its principals and hope that the Attorney General will realize this upon further reflection," the company said in a blog post.

The post said that Craigslist has worked closely with state prosecutors and "decreased misuse dramatically" in the last six months.

"Given the progress that has been made dealing with these tremendously complex issues in a very short time, and the ongoing collaboration between Craigslist and law enforcement to make further improvements, we urge Attorney General McMaster to look closely at the facts before proceeding with his threat," Craigslist explained in the post.