LAKEWOOD RANCH -- Stephen Sajewski, founding principal of Imagine Charter School at Lakewood Ranch, has resigned.

The resignation was by mutual agreement, several members of the schools governance board confirmed Tuesday.

In a span of about four years, Sajewski, 35, helped build an enrollment of more than 500 students.

The school, located at 10535 Portal Crossing, received a C grade this year, after earning a B grade in 2011 and 2010.

"He wants to pursue something different," governance board member Christy Bryans said, applauding Sajewski for growing enrollment "from something so small."

In a letter to Imagine Charter School parents, Sajewski wrote in part:

"Friday, June 29, 2012, was my last day as school leader of Imagine Charter School at Lakewood Ranch. Simply put, this is a mutual parting of ways between myself and Imagine Schools. This was a difficult decision, but one that was made with the best interest of all shareholders of Imagine School at Lakewood Ranch in mind."

The Herald was unable to contact Sajewski Tuesday night for comment or elaboration.

Verdya Bradley, associate director of innovative programs for the Manatee School District, said she was caught off guard by the departure.

"I was quite surprised. I had not heard of any problems," Bradley said.

Members of Imagine's governance board referred other questions to Chris Watson, director of the West Florida Region of Imagine Charter Schools and Sajewski's supervisor.

"I have known Mr. Sajewski for as long as we have both been at Imagine Charter Schools," Watson told the Herald in a phone interview. "I respect him for the good work that he has done at more than one Imagine Charter School."

During a recent conversation with Sajewski, Watson said she suggested that this might be a good opportunity for a new leader to "cast another set of eyes on the school and potential areas for growth."

Asked whether the handling of a recent attack by a student on a teacher played a role, Watson declined to comment.

Interviews have already started on finding a replacement, and three finalists have been identified, she said.

"It is our hope that we will have the right person ready to present to the board in the next week or two," Watson said.

James A. Jones Jr., East Manatee editor, can be contacted at 941-745-7021 or tweet@jajones1