Judge Christopher Dee declared a mistrial around 1:10 p.m. Wednesday, after jurors deliberated for two and a half days.
"I thank you for putting in the time that was so critically important in this case," Dee told the jurors before he dismissed them.
The jury took in two weeks of testimony in the case.
The Milwaukee County District Attorney's office will now have to decide whether or not to attempt the trial again.
"I'll talk to the lead prosecutor on the case, talk to the victim and the victim's attorney," said Milwaukee County District Attorney John Chisholm. "I will also sit down with the defense attorney, and we'll determine where we go in the future."