The Inquisitors - The Space Merchants Series, #6

Fear is weakness. Control is power. He betrayed her parents, left her to be raised by a sadistic Earth Loyalist, had her abducted by his clones, and murdered one of her beloved husbands before her eyes. Now, he is trying to destroy the Parvac Empire from within. Many have tried and failed to capture the elusive Felix Jiri, but one man is determined to succeed. The Inquisitors of the Parvac Empire deal in secrets, justice, and death.
Feared for their ruthlessness and use of torture, they gather intelligence and punish lawbreakers, even if it means tracking an offender down across galaxies. Serving as judge, jury, and executioner, they must serve loyally without allowing their personal feelings to affect their judgement. However, protecting Princess Teagan is personal, and Inquisitor Eli Beck will go to any lengths to bring Felix Jiri to justice, even if he must sacrifice his relationship with her to do it.