Red-faced city Department of Education officials are trying to figure out how a principal forced out amid allegations of test-tampering at a failing Manhattan high school in 2008 wound up running an elementary school this year.

John Angelet resigned under pressure from the F-rated Bayard Rustin HS last June during a lengthy probe of his alleged role in changing students’ Regents test scores.

The school’s graduation rate dipped as low as 47 percent — down from 54 percent in 2004 — during Angelet’s four years at the helm, and the school was tagged for closure.

His surprising appointment as interim principal of PS 101 in East Harlem this July — while the Office of Special Investigations continues its cheating probe — appeared to catch top education officials off guard.

On Friday, Angelet was pulled from PS 101 “effective immediately,” a Department of Education spokeswoman said.