The principal of Manual High School — the once-promising school whose struggles with low performance Chalkbeat Colorado documented last week — left the school abruptly Thursday, telling staff it was at the behest of the district.

“With great sadness I must announce that the district has decided that I will no longer be the Principal at Manual,” Brian Dale told his staff in an email obtained by Chalkbeat Colorado. “I heard today, effective today. Thank you all for the incredible work that you have done to create possibilities for our scholars. It has been a great pleasure, every day! Best wishes to all of you. Brian”

A district representative confirmed Dale was leaving but not that he had been fired.

It’s unclear how the decision will affect the rest of the school year for Manual.

“We will work with the Manual community starting tomorrow on a short-term and long-term transition plan,” Alyssa Whitehead-Bust, the district’s chief innovation officer and Dale’s immediate supervisor, said of the leadership shuffle. “Our focus is on kids — students first.”

Assistant principal Vernon Jones said he was “still processing” the information.

During Dale’s tenure, the school saw a dramatic drop in student performance on state exams. Last year, the school posted the lowest scores on the tests since the school was closed in 2006 and re-opened a year later.

Dale became principal of the school in 2011, four years after district officials re-started the school with promises that they would rebuild a premiere high school for its mostly impoverished student body. Dale was hired after the school’s first turnaround principal, Rob Stein, resigned over conflicts with district administration.

The downward trend in academic proficiency and growth coincided with Dale’s implementation of a new school model which sent students across the nation to historic social justice landmarks like Little Rock, Ark. and Memphis, Tenn. The goal was to foster student engagement and provide examples of “social revolutionaries” whom the students could model.

Additionally, Dale and his team overspent the school’s budget by $600,000 after they failed to raise enough money to pay for the trips. Part of school’s plan to repay the district included Dale taking a 92 percent budget cut.

Asked if Dale’s exit was due in part to any situation other than what Chalkbeat Colorado reported, Whitehead-Bust said: “I doubt it.”

Throughout its history, Manual, the city’s oldest high school, has been the center of education reform in the city. The school has educated some of the city’s most active civil servants and activists including former Mayor Wellington Webb and current Mayor Michael Hancock. When the Denver school board decided to close the school in 2007, it was met with public outcry. The school would reopen and be the envy of the nation, then-superintendent Michael Bennet said.