Hi,
I have recently read a detective serial thriller novel. Protagonist is male FBI Detective.
Assistant protagonist female detective
Plays chess with himself
When asked to check older crime scene he avoids, waits for next crime and goes to inspect crime scene
Protagonist beats the local jurisdiction head cop in the restroom, head cop explains he fell down in restroom
Please help me to find the series so I can read next book in the series.

Do you remember if the book's title was chess-themed as well (Opening Moves, The Pawn, The Rook, something like that)? If so, it sounds like this might be the Patrick Bower Files series by Steven James.

Thanks for the reply. I have read Bowers files Steven James. It's some other book.