Acting Freddie Mac Chief Financial Officer David B. Kellermann “worked himself into a frazzle” before his apparent suicide early Wednesday, according to a co-worker. Police found Kellermann hanging in the basement of his suburban home he shares with his wife and 5-year-old daughter outside Washington, D.C. Colleagues said he was fun-loving, upbeat, and popular at Freddie Mac, the government-backed mortgage company that has been under investigation by federal authorities the past few months. Kellermann, 41, joined the firm in 1992 and was appointed CFO just last September, when the government seized control of the company. He also was due to receive about $850,000 in bonuses this year thanks to a controversial bonus program designed to retain talent in a demoralizing atmosphere.