The alleged offenses reportedly occurred in Lee County.
Accused in 2013 indictments are Dennis John Papez, 56, of Saltillo; Casey C. Holmes, 29, of Albuquerque, N.M.; and James Rudy Leach, 41, of Nettleton.
Each is accused of using Internet and cellular telephone communications to attempt the sexual activity, which could be prosecuted under Mississippi laws as statutory rape and sexual battery.
In the cases of Papez and Holmes, the government also asked for forfeit of a vehicle “that was used or intended to be use” in the alleged offenses.
Punishment for such a conviction ranges from no less than 10 years in prison to life and up to $250,000 fine.
Wednesday, Papez was ordered detained after he pleaded not guilty. His trial was set for April 15.
After Holmes pleaded not guilty, he was released with one condition to seek mental health treatment if necessary.
Leach pleaded not guilty, continued to be detained and is set for trial April 22.
In a fourth case, Chief U.S. District Judge Michael P. Mills declined to throw out the 2011 conviction and 120-month sentence of James Allen Richardson, who pleaded guilty to using the Internet to try to persuade a 15-year-old to have sex with him.
Richardson, 46, of Myrtle, was alleged to have attempted the crime in Lee County.
In his appeal, he claimed ineffective counsel, an illegal search and entrapment.
Mills wrote in his eight-page ruling that Richardson had missed all deadlines to properly file appeals and the judge denied any further appeals.