Lafave, a teacher at Valley High School in Las Vegas, was allegedly caught having sex with the 16-year-old boy by a hall monitor.
The teenager has special educational needs and does not know right from wrong, it was reported.
The pair are believed to have spent time together nearly every day and exchanged thousands of text messages, the arrest report allegedly shows.
Lafave was released on bail following her arrest on January 16 and has been placed on administrative leave from the school.
She is due to appear in court in March.
