Illinois Municipal Retirement Fund, Oakbrook, is interviewing three finalists in its search for an enhanced domestic fixed-income manager. BlackRock, Lincoln Capital and FIRMCO will appear before the $14.5 billion funds investment committee. A firm may be hired to manage the new $500 million portfolio later this month or sometime in January, said Walter Koziol, director of investment for the fund. Board members are looking at a low-risk approach that can add alpha with low volatility, he said. The source of funding will be decided in January.