Angel Heart

In 1955, Harry Angel, a New York City private investigator, is hired by Louis Cyphre to track down John Liebling, a crooner known as "Johnny Favorite" who Cyphre had helped become successful. Cyphre stands to benefit from unspecified collateral on Favorite's death and suspects that a private upstate hospital, where the war invalid Favorite was receiving psychiatric treatment for shell shock, is issuing false reports. Angel goes to the hospital and discovers that a backdated transfer record has recently been added by a physician named Albert Fowler. After Angel breaks into his home, Fowler admits that 12 years ago he was bribed by a man and woman to allow Favorite to leave while maintaining the fiction that he was still a patient at the hospital. Believing that Fowler is still withholding information, Angel locks him in his bedroom. Hours later, he finds the doctor murdered.
Unnerved, Angel tells Cyphre that he no longer wants the job, but agrees to continue after Cyphre offers him $5,000. He soon discovers that Favorite had a wealthy fiancÃ©e named Margaret Krusemark but had also begun a secret love affair with a woman named Evangeline Proudfoot. Angel travels to New Orleans and meets with Margaret, who divulges little information, telling him that Favorite is dead. Angel then discovers that Evangeline is also dead, but is survived by her 17-year-old daughter, Epiphany Proudfoot, who was conceived during her mother's love affair with Favorite. When Epiphany is reluctant to speak, Angel tracks down Toots Sweet, a blues guitarist and former Favorite bandmate. After Angel uses force to try to extract details of Favorite's last-known whereabouts, Toots refers him back to Margaret. The following morning, police detectives inform Angel that Toots has been murdered. Angel returns to Margaret's home, where he finds her murdered, her heart removed with a ceremonial knife. He is later attacked by enforcers of Ethan Krusemarkâa powerful Louisiana patriarch and Margaret's fatherâwho tell him to leave town.
Angel returns to his hotel and finds Epiphany on his doorstep. He invites her into his room, where they have aggressive sexual intercourse, during which Angel has visions of blood dripping from the ceiling and splashing around the room. He later confronts Krusemark in a gumbo hut, where the latter reveals that he and Margaret were the ones who helped Favorite leave the hospital. He also explains that Favorite was actually a powerful magician who sold his soul to Satan in exchange for stardom, but then sought to renege on the bargain. In 1943, Favorite kidnapped a young soldier and performed a Satanic ritual on the boy, murdering him and eating his still-beating heart in order to hide from the devil. Angel has a panic attack and runs into the bathroom. He returns to find Krusemark drowned in a cauldron of boiling gumbo.
Angel goes to Margaret's home, where he finds a vase containing a clue to the soldier's identity: a set of dog tags with his name stamped on them. Cyphre then appears, and Angel deduces that "Louis Cyphre" is a homophone for Lucifer. Cyphre confirms that he is the devil and proclaims that he can at long last claim what is his: Favorite's immortal soul. In a fugue state that Cyphre induces, it is revealed that Angel has murdered Fowler, Toots, the Krusemarks and Epiphany.
A frantic Angel returns to his hotel room, where the police have found Epiphany raped, brutally murdered and wearing Angel's dog tags. When Angel reveals that Epiphany was his daughter, a detective tells him that he will "burn" for what he has done to her, to which Angel replies, "I know. In Hell." During the end credits, Angel is seen standing inside an iron Otis elevator which is interminably descending. As the screen fades to black, Cyphre can be heard whispering, "Harry" and "Johnny", announcing his dominion over both their shared souls.[3]

Question: Who is  the New York City private investigator?
Answer: Harry Angel.