FORT COLLINS, Colo. -- A former Brighton Charter school teacher facing charges of sexual assault on a student waived her preliminary hearing Thursday.

"That means they're conceding probable cause at this point," said Larimer County District Attorney Larry Abrahamson.

Carrie McCandless, 28, carried on a romance with a 17-year-old student at Brighton Charter School, according to her arrest affidavit. The affair included 76 text messages from her to the student in a single day, an arrest affidavit alleged.

McCandless is married to the principal of the high school and was fired from her job as teacher and cheerleader coach.

She faces felony charges of sexual assault on a child by one in a position of trust and contributing to the delinquency of a minor. The second charge involves allegations she provided alcohol during a school trip to the Estes Park area last October.

Although school officials learned of the allegations the Monday after the trip and recovered notes between the two, police said they were not called and learned about the allegations when a reporter called to ask about the case.

Brighton Charter School Board President David Mundy was charged with felony tampering with a witness or victim and misdemeanor failure to report child abuse in connection with the case. He resigned from the board after he was charged.

On Thursday, McCandless waived her preliminary hearing on the charges against her so she and her attorney could continue to discuss a possible plea deal with the district attorney's office.

McCandless faces an additional charge of violating her bond by allegedly contacting the 17-year-old by phone. She denies the charge.

"It's very difficult to reach a plea agreement in a sex assault case," said former Denver chief deputy district attorney Karen Steinhauser. Strict sentencing laws can require that sex offenders spend many years in prison ... on parole ... or on probation. "Another requirement with people who are convicted whether by a jury, or plead guilty to certain types of sex offenses, like this one, is that they also have to register for the rest of their life as a sex offender."

McCandless' attorney M. Trent Trani told the judge his client was "waiving her right to a preliminary hearing to keep plea negotiations open."

McCandless is due in back court on April 24 for a for a status hearing or disposition of both charges.