Kellermann usually brought a three-page list of to-do items. Moffett was new to the company, appointed by the government after it seized Freddie Mac in September, and he recalled leaning heavily on Kellermann's 16 years of experience at the firm for guidance.  Kellermann, 41, was found dead yesterday morning in his Fairfax County home in an apparent suicide, police said. He left no note, law enforcement sources said, and his motivations were not known.  But even if his final act was unrelated to work, his last months were consumed by the mounting stresses at the center of the financial crisis. People who knew him said he was deeply committed to Freddie Mac, just about the only place he'd worked professionally, and its struggles had taken an increasingly visible toll.  "David was engaged in all parts of the company," said Moffett, who tapped Kellermann as his chief financial officer before resigning the top post last month. "The CFO of any company in today's environment is a very stressful job . . . particularly when you're in a company that's undergoing a tremendous amount of change and uncertainty."  Kellermann had worked his way up at Freddie Mac from a young financial analyst to one of the mortgage giant's main points of contact with its government overseers. Recently, he'd faced intense pressures dealing with the company's billions of dollars in losses and myriad other accounting and legal issues, refusing to take time off, his colleagues said.  "He endured a tremendous amount of stress over the years . . . It's been a difficult environment," said Peter Federico, Freddie Mac's treasurer and a close friend. The news of Kellermann's death yesterday stunned his colleagues. "It's one of the things that puts everything in perspective. It's difficult for everybody to deal with it," Federico said.  Kellermann was found by his wife, Donna, yesterday in the basement of their home in the upscale Hunter Mill Estates subdivision in Vienna, law enforcement sources said. He had hanged himself on a piece of exercise equipment, the sources said. There were no signs of foul play. His body was taken to the office of the medical examiner, who will rule on the cause of death.  Soon after Kellermann's death was reported, television trucks pulled up outside his stately brick home and its manicured lawn, beaming the image around the world. Many neighbors were taken aback by the attention given to the apparent suicide.  Susan Unger, a neighbor, said she last saw him a few weeks ago working in his yard. She woke up early yesterday morning to the sound of rescue crews arriving. "They took the stretcher in and brought it out empty, so I thought everything was okay," Unger said. "It's just so sad. . . . I'm just in total shock."  The neighbors knew Kellermann mostly as a doting father of a young daughter and meticulous gardener. He decorated his home lavishly for Christmas and threw great parties for Halloween and University of Michigan football games. He'd attended Michigan before receiving a graduate degree from George Washington University.  But Sergio Moreno, who lives up the street, said he had recently noticed some changes. Kellermann was busier than ever and more stressed. A large man, Kellermann had lost a lot of weight.
In the months before he died, David B. Kellermann would trek most evenings to Freddie Mac's executive suite to see his boss. Long after other employees had headed home from the McLean campus, Kellermann, the acting chief financial officer, would remain cloistered with chief executive David Moffet...