context: A voiceover says that this is the story of how the narrator almost died.
  Philadelphia Police Detective John Hobbes visits serial killer named Edgar Reese, who he helped capture, on death row. Reese grabs Hobbes' hand and says something in an unknown language, later identified as Aramaic. After Reese is executed, Hobbes and his partner Jonesy investigate a string of murders by an apparent copycat killer. Hobbes, through hints given initially by Reese, and later by the apparent copycat killer, tracks down a woman named Gretta Milano, the daughter of a former detective. Gretta explains that her father, a detective in the same city killed himself after being accused of a series of demonic-themed murders. Hobbes goes to the Milano family's lake-house, and finds books concerning demonic possession, and sees the name Azazel written on a wall.
  Hobbes inquires after the name to Gretta, who gravely advises him to drop the case to protect his life and family. Gretta explains that Azazel is a fallen angel with the power to possess human beings by touch. Hobbes realizes that Azazel, while possessing Edgar Reese, touched Hobbes before the execution, but was not able to possess him. Gretta explains that the demon will try to ruin his life by another way, and warns him of the inevitability of Azazel's victory. Azazel finds Hobbes at his precinct, and through his coworkers, torments him. Hobbes reveals his knowledge of Azazel's true identity, to which the demon responds, "Beware my wrath", and disappears into the city.
  To provoke Hobbes, Azazel possesses his nephew Sam and attacks John's intellectually disabled brother Art in their home. He flees into other people on the street, ending up in a schoolteacher. As the teacher, Azazel draws a gun and forces Hobbes to shoot his host in front of a group of bystanders. Azazel boasts to Hobbes that even if his current host body is killed, he can transfer to any new host body in the surrounding area, without even needing to touch them.
  Lieutenant Stanton informs Hobbes that his fingerprints were found at one of the murder scenes and along with the bizarre circumstances of the shooting of the teacher Azazel possessed, he has become a suspect for all the murders. Azazel inhabits several of the witnesses and gives false accounts that the shooting was unprovoked, thereby throwing further suspicion on Hobbes, framing him for the crime. He also comes into his home and murders his brother, whilst also marking Sam. Hobbes then takes his nephew to Gretta's house, to keep him safe.
  Hobbes, after consulting with Gretta, formulates a plan to end Azazel. He escapes to the lakeside cabin where he originally found Azazel's name and draws the demon to him. Stanton and Jonesy show up, to talk to Hobbes. Jonesy, possessed by Azazel, kills Stanton and pursues Hobbes into the cabin. After ambushing the demon, Hobbes shoots Jonesy in the stomach. Azazel takes possession of Hobbes' body and learns that Hobbes has poisoned himself. He frantically searches the remote wilderness for another host, but succumbs to the poison and dies. Azazel, in a voiceover, reminds the viewer this is the story of how he almost died. A cat, who becomes possessed by Azazel, emerges from underneath the cabin.
question: What is Edgar Reese?
answer: A Serial killer.