A federal judge in Boston has sentenced the mastermind of a college admissions scam to three-and-a-half years in prison over a scheme where wealthy parents paid exorbitant bribes to secure spots for their unqualified children in prestigious universities. In some cases, photos were staged or doctored to make the teenagers seem like accomplished athletes. William “Rick” Singer received the sentence Wednesday, nearly three years after he pleaded guilty to criminal charges including racketeering, money laundering and obstruction of justice. Singer’s clients included Hollywood stars Felicity Huffman and Lori Loughlin, and Bill McGlashan, a founder of TPG Capital, one of the largest private equity investment firms in the world.