Free fall by Robert Crais

Elvis is back. No, not that one . . . the good one, the one who's
fun to read about. Elvis Cole, Los Angeles private eye, returns in the
fourth installment of a series in which there is way too much time
between installments. Jennifer Sheridan wants Elvis to find out what's
bothering her fiance, Mark Thurman, an undercover cop with an elite
LAPD unit. Jennifer is certain it's not another woman, but Thurman
himself tells Elvis the opposite. Elvis breaks the news to Jennifer in
a hilarious restaurant scene, but she convinces him to stay on the
case. Inevitably, Jennifer's suspicions turn out to be more than
wishful thinking. Take the Rodney King case and put this spin on it:
the guy with the camera was more interested in blackmail than justice.
Pretty soon Elvis and his borderline sociopath partner, Joe Pike, are
up to their smoking guns in renegade cops and angry gangs. Crais, who
also writes for television ("L.A. Law," "Hill Street Blues"), has
created a series hero who is tough, witty, resourceful, and even
romantic. Let's face it: we all want to be Elvis Cole when we grow up.