The 35-year-old mother allowed at least seven men to have sex with her 14-year-old at least 20 times, the patrol said. Investigators also said at least three men had sex with the 7-year-old.
The Lincoln Journal Star reported Thursday that three men have been arrested and charged with sexual assault of a child. The felony carries a prison sentence of 20 years to life.
"This is a very disturbing case," said patrol Superintendent David Sankey. "Our investigators working this case have nearly 30 years of experience and cannot recall a time where children so young were being sold into prostitution."
The woman was arrested April 26 at a Kearney motel after offering her daughter for $200 to an undercover officer, the patrol said.
The mother was charged with child pornography and with conspiracy to commit sexual assault of a child. She remained in Buffalo County jail on Thursday, pending $250,000 bond. The Associated Press is not using her name, to protect the identity of the girls.
The mother's attorney did not immediately respond to a message left by The Associated Press.
Court records indicate the woman has three daughters, but the Nebraska State Patrol has mentioned only two of them in the allegations. All three have been placed in the state's care.
"We've seen people make horrible decisions and commit horrible crimes for a variety of reasons," said Buffalo County's chief prosecutor, County Attorney Shawn Eatherton. "Trying to figure out why people do the things they do is a tough task."