Both games have the barest connections to the actual movie. Here's the description of the first game:
"Step into the shoes of Erica Dean as she investigates crime scenes in New York City. It`s a man hunt for a vigilante on a killing spree through 16 locations containing over a thousand hidden objects. With the help of Sergeant Vasquez, Erica will use clues she collects in a number of detective-themed mini games. Inspired by the motion picture film, Righteous Kill features clips from the movie and 15 animated levels."
(Who is Erica Dean and why does she need Sergeant Vasquez's help?)
And here's a description of the second:
"As an investigator in the NYPD, hunt down a copycat killer and try to stop a rash of murders across New York City! Work through multiple murder scenes, collecting evidence and clues, and examine the items in exciting forensic based mini-games. Put all the clues together to determine who the new Poet Killer is before another victim is found, and decide who to trust as the suspects begin to include those inside the police force."
In case you get stuck, there's even a blog walkthrough.
Those Resident Evil movies are sounding better all the time. At least they had skinless zombie dogs.