During the interrogation Matthew Modine's character breaks down and yells "I am a psycho killer!" This is both a reference to and a quote from the famous line spoken by Pvt. Joker in the film Full Metal Jacket (1987), a character also played by Matthew Modine.
Det. Tutuola (Ice-T) says of his father "I do too, but mines stuck around, not like your daddy". In real-life, Ice-T's mother died of a heart attack when he was in third grade. His father, Solomon, raised him as a single father for four years, with help from a housekeeper. When Ice-T was was thirteen years old, his dad also died of a heart attack.
Det. Munch (Richard Belzer) references quote "The truth will set you free". This originated from John 8: 31 and 32 of the Bible. The full quote is, "If you hold to my teaching, you are really my disciples. Then you will know the truth, and the truth will set you free".
Doctors Without Borders, is a charity that provides humanitarian medical care in more than 70 countries. They offer assistance to people based solely on need, irrespective of race, religion, gender, or political affiliation.