A news conference is planned Monday after a third Stamford High School administrator was placed on leave.

Assistant Principal Angela Thomas-Graves was placed on leave Friday, according to district officials. The news conference is planned at the city's Government Center.

Principal Donna Valentine and Assistant Principal Roth Nordin were previously placed on leave for allegedly failing to report a suspected sexual relationship between a teacher and student.

It is unclear whether the latest suspension is related to Valentine and Nordin's suspension involving former teacher Danielle Watkins.

Watkins, a 32-year-old married mother of two, pleaded guilty earlier this month to sexual assault and risk of injury to a minor. She acknowledged that she did have a sexual relationship with a 17-year-old student while she was an English teacher at the school.

She was also accused of giving marijuana to him and another student. The victim's attorney, Devin Janosov, said Watkins instigated the relationship.

As part of her plea deal, Watkins is expected to face up to four years in prison when she is sentenced in 2015.

She will also be required to register as a sex offender for the next 10 years.