James Patterson and David Ellis

Invisible series (#1-2)

Invisible (#1): Everyone thinks Emmy Dockery is crazy. Obsessed with finding the link between hundreds of unsolved cases, Emmy has taken leave from her job as an FBI researcher. Now all she has are the newspaper clippings that wallpaper her bedroom, and her recurring nightmares of an all-consuming fire.
Not even Emmy’s ex-boyfriend, field agent Harrison “Books” Bookman, will believe her that hundreds of kidnappings, rapes, and murders are all connected. That is, until Emmy finds a piece of evidence he can’t afford to ignore. More murders are reported by the day–and they’re all inexplicable. No motives, no murder weapons, no suspects. Could one person really be responsible for these unthinkable crimes?

Unsolved (#2): The perfect murder always looks like an accident.
FBI agent Emmy Dockery is absolutely relentless. She's young and driven, and her unique skill at seeing connections others miss has brought her an impressive string of arrests.
But a shocking new case-unfolding across the country-has left her utterly baffled.
The victims all appear to have died by accident, and have seemingly nothing in common. But this many deaths can't be coincidence. And the killer is somehow one step ahead of every move Dockery makes. How?