Under the plea agreement Eric Crader will face 50-100 years in prison.
The jury returned the verdict against Omar Best shortly before 9 p.m. Tuesday.
Police say the 45-year-old man raped three girls over more than a decade.
The suspect is charged with multiple offenses.
The 29-year-old teacher was removed from the school in handcuffs.
Police say they were tipped-off by suspect's family