Fair Warning by Michael Connelly

When reporter Jack McEvoy is interviewed by the LAPD as a possible suspect in the murder of a woman he dated once, his interest is piqued and he decides to look into the case. Jack discovers that her death might be connected to several other women's, since all were killed in a similar way and they had also all undergone genetic testing with the same company. The police want Jack to stop investigating and let them do their job, but Jack continues on with the help from a colleague and ex-FBI agent Rachel Walling. Soon, they find themselves involved with a far bigger case and foe than they could have ever imagined... Fair Warning will be published later this month.