Hunted to Death

A sniper? In Bel Air?
The peace of wealthy Bel Air is shattered on a Friday night by a rifle shot. Anyone who's outdoors in the neighborhood hears the shot, including Kevin Brodie and Kristen Beach, but no one knows where the shot came from or the identity of the intended target...until the next day, when Jamie Brodie brings his dog, Ammo, to Kevin's house.
Ammo, a trained cadaver dog, drags Jamie and Kevin up the street about a half-mile then alerts on a house. The officers who respond to Kevin's 911 call find a man lying on his pool deck, shot in the head by a high-caliber round. The victim is identified as 72-year-old Dean Stokes, a tier three registered sex offender who was released from incarceration in Kansas four months before.
The logical assumption is that one of Dean's victims waited 35 years to get their revenge. Dean's sister thinks so; she jets in from St. Louis and hires Angeles Investigations to solve Dean's murder, but she's withholding information. Why?
When the Angeles team realizes that their answers probably lie in Missouri, they also realize that they'll need help. Good thing that their administrative assistant, Ryan McKinney, has a cousin in St. Louis who's a PI.