A former senior financial analyst at the failed mortgage lender Taylor, Bean & Whitaker Mortgage Corp. pleaded guilty Thursday to charges connected to an alleged $1.5 billion fraud scheme. Sean Ragland pleaded guilty in a Virginia federal court to one count of conspiring to commit bank and wire fraud, the Justice Department said. Ragland is the fifth person associated with the defunct mortgage lender to plead guilty. His plea comes ahead of the start of a criminal trial against Taylor Bean’s former chairman, Lee Farkas, which begins Monday. Prosecutors allege that Taylor Bean started to experience financial problems as far back as 2002 and was unable to cover its expenses. They alleged that Farkas and other executives concocted a series of fraudulent transactions to keep the company afloat, including an attempt to defraud the federal bank bailout of $550 million.