"I'm truly sorry for what I've done," he told the judge. "I know under the circumstances that's hard for you to believe."
Arms folded across his chest, eyes glancing down at his watch, the judge snapped back: "It is."
Skief is the eighth Philadelphia charter school official to plead guilty to federal fraud charges. His three-year sentence exceeds by nearly a year the prison term originally proposed by prosecutors before his continued theft came to light.
In addition, Diamond barred Skief from reestablishing ties to Harambee or taking an administrative role at any other school for three years after his release. Diamond also ordered Skief to pay back $88,000 to the Harambee Institute, a nonprofit tied to the school.
Prosecutors said that between the time he signed his plea agreement in May and he pleaded guilty in August, Skief used an institute debit card 43 times, spending nearly $12,000 - including one charge on the day he was due in court to enter his plea.
Five more charges for parking near his lawyer's office and for ATM cash withdrawals showed up in the nine days after Skief admitted his guilt
That money came on top of the more than $79,000 he originally admitted to stealing from the institute and the $9,000 he took from a scholarship fund established in the memory of his father.
He spent it on personal expenses, including flowers, hotel rooms for his girlfriend, auto repairs, and to put a down payment on a house, prosecutors said.
"You see a history of the defendant simply stealing from Harambee Institute whenever he had the opportunity and never, never stopping," First Assistant U.S. Attorney Louis Lappen said. "This is not a case of having a bad day and making one mistake."
Even Skief's lawyer, Gregory Miller, appeared at a loss Monday to explain his client's actions. In addressing the court, he sounded at times more like a disappointed father than an attorney advocating on his client's behalf.
"I detected a degree of rationalization that seemed a little troubling with Masai," Miller said.
Still, more than 60 Harambee teachers, former students, and friends submitted letters to Diamond extolling Skief's record as passionate educator and sterling role model to his 15-year-old son, Naeem.
A graduate of Florida A&M University with a master's degree in education from Drexel University, Skief began teaching science at Harambee in 2004. He was elevated to its executive office three years later, at the age of 26, when his father, John, died.
The West Philadelphia school, which opened in 1997, is one of the oldest charters in the state and has called itself Pennsylvania's first African-centered charter school.
Some of Skief's supporters said Monday they saw the questioned transactions not as theft but as a matter of shoddy bookkeeping. Skief often spent part of his own $100,000 annual salary on Harambee's behalf, they said.
But the former charter executive maintained the time for such excuses had passed.
"I went through spells of ignorance and deflection and even some arrogance before it clicked and I really got what I had done," Skief said. "Where I am now after preparing for this sentence is a totally different place than when I felt I was being victimized."