CAPITAL CRIMES --- a worthy successor to 2004's DOUBLE HOMICIDE --- is the second in what hopefully will be an ongoing series of collaborations between Jonathan and Faye Kellerman. The premise of this experiment is an interesting one: each volume contains two novellas involving characters previously unknown within the Kellermans' respective worlds, set in cities other than Los Angeles. The husband-and-wife writing team ostensibly collaborates on each work, though "My Sister's Keeper," which takes place in Berkeley, California, seems more Faye than Jona