Desert Saints

Desert Saints is a 2002 crime thriller film starring Kiefer Sutherland as a hitman named Arthur Banks, alongside Melora Walters as Agent Bennie Harper. The film is produced by Meg Ryan.

Thinking quickly, the agent pretends to be Harpers jealous and abusive exhusband, but this plan goes awry when Banks, who seems more interested in Harper than normal, kills the agent out of Harpers sight and then disposes of the body in a manner not witnessed by Harper incineration, leaving the FBI once again with no evidence to arrest him. That night, Banks and Harper become lovers at a remote motel. Scanlon decides to cancel the sting after the agents death and to withdraw Harper, but Harper talks him out of it, pointing out that Banks is their only lead to his employers in the drug cartels. On the road, Banks confides to Harper that he hates his job but hasnt had a chance to get out of it for years until now.In Mexico, Harper doublecrosses both Banks and the FBI, first shooting Banks to stop him from committing the assassination and handcuffing him to the balcony, but then killing the thugs who hired him and taking their key for the payoff from the hit. She tells Banks that she expects the FBI will be so happy to catch and question him that shell depart with the payoff without much problem, which is why she leaves him alive. However, by the time Scanlon responds to her call on Banks location, he has escaped. Meanwhile, the FBI agents follow Agent Marburys sighting of a fleeing Harper to the local airport, only to lose her there, because the sighting was actually Marbury herself in a disguise, which she sheds in a washroom, permitting Harpers undetected escape. ........

Source: Wikipedia