Marks' last day will be Aug. 17. She said she was for leaving for personal reasons, Chiramonte said.
Marks demonstrated leadership during her two-year tenure despite “challenging financial circumstances largely beyond her control," he added.
“Student test scores have been up across the board. We were rated the school system that made the most progress of the 18 largest school districts in Connecticut in systematic use of data and staff professional development, according to Warren Logee of the State Board of Education," Chiramonte said.
Neither Marks nor Norwalk Mayor Richard Moccia could be immediately reached for comment Friday.
Norwalk's public schools have struggled over the past few months to close a multi-million budget gap. Marks' resignation comes a day after Chiramonte and the Board of Education approved a new spending plan with $6 million in cuts, including teacher lay-offs.
Parent and schools activist Barbara Smyth called the timing of Marks' announcement "shocking."
"We’re dealing with a profound budget crisis and to be leaderless at a time like this is deeply concerning," said Smyth, who organized a series of recent rallies against the budget cuts. “I’m really concerned about our district moving forward.”
Lisa Thomson, another parent and schools activist who runs the website www.redapples.com, said students were always Marks' primary focus.
“Susan was a quiet leader. She knew all the things to do and she was building a foundation for Norwalk, and that’s going to come out,” Thomson said.
Marks had considered taking a leave of absence in September, again citing personal reasons.
Until her last day, Marks will help the board of education on a transition plan, Chiramonte said.