Question: The Angel of Darkness is the sequel to The Alienist written by whom? 

Context articles: Angel of Darkness (book)
Fallen angel
Darkness Descends
Angel of Darkness (song)
The Alienist
You're Welcome (Angel)
The Angel of Darkness
Caleb Carr
Deep in the Darkness
Piercing the Darkness

Angel of Darkness: The True Story of Randy Kraft and the Most Heinous Murder Spree of the Century is a non-fiction book by investigative journalist and American author Dennis McDougal published in 1991 by the Hachette Book Group.
 McDougal was an investigative reporter for the "Long Beach Press-Telegram" assigned to cover the case when Kraft was arrested.
 At the time "Angel of Darkness" was released, McDougal was working as a reporter for the "Los Angeles Times".
A fallen angel is a wicked or rebellious angel that has been cast out of heaven.
 The term "fallen angel" does not appear in the Bible, but it is used of angels who sinned (such as those referred to in , "For if God did not spare angels when they sinned, but cast them into hell and committed them to chains of gloomy darkness to be kept until the judgment ..."), of angels cast down to the earth in the War in Heaven, of Satan (Lucifer), demons, or of certain Watchers.
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Darkness Descends is the second studio album by the American thrash metal band Dark Angel.
 The album is the first to feature drummer Gene Hoglan.
 Rob Yahn was replaced with Mike Gonzalez by the time this album was released, however, Gonzalez was given credit over Yahn on the album sleeve.
 "Darkness Descends" was also Dark Angel's final album to feature vocalist Don Doty.
 The album is considered a landmark in the thrash metal genre.
"Angel of Darkness" is the third single by German composer Alex Christensen featuring vocals from Yasmin Knoch, which was released in 2003 by Epic Records.
 The song has peaked at number 21 on the German singles chart.
 This song was also released with the video game Tomb Raider: The Angel of Darkness.
The Alienist is a crime novel by Caleb Carr first published in 1994 and is the first book in the Kreizler series.
 It takes place in New York City in 1896, and includes appearances by many famous figures of New York society in that era, including Theodore Roosevelt and J. P. Morgan.
 The sequel to the novel is "The Angel of Darkness".
 The story follows Roosevelt, then New York City police commissioner, and Dr. Laszlo Kreizler, as their investigative team attempts to solve gruesome murders through new methods including fingerprinting and psychology.
 The first murder victim investigated is a 13-year-old immigrant who has had his eyes removed, his genitals removed and stuffed in his mouth, and other injuries.
 The investigators deal with various interest groups that wish to maintain the status quo regarding the poor immigrant population in New York City.
"You're Welcome" is the twelfth episode of season five of the television show "Angel".
 Written and directed by David Fury, it is the 100th episode of the series, and originally broadcast on February 4, 2004 on the WB network.
 In "You're Welcome," former series regular Charisma Carpenter returns as a guest star, when the character of Cordelia Chase miraculously awakens from her coma.
 It is her duty to put Angel, who has recently been feeling ineffective at fighting the powers of darkness, back on the right path.
 Meanwhile, Angel's old enemy Lindsey McDonald has resurfaced and is plotting revenge.
 The episode features the death and final onscreen appearance of Cordelia.
The Angel of Darkness is a 1997 crime novel by Caleb Carr that was published by Random House (ISBN  ) and is a sequel to "The Alienist" (1994), and is the second book in the Kreizler series.
Caleb Carr is a military historian and author born August 2, 1955 in New York, New York.
 Carr is the second of three sons born to Lucien Carr and Francesca Von Hartz.
 He is the critically acclaimed author of "The Alienist, The Angel of Darkness, The Lessons of Terror, Killing Time, The Devil Soldier, The Italian Secretary," and "The Legend of Broken".
 He has taught military history at Bard College, and worked extensively in film, television, and the theater.
 His military and political writings have appeared in numerous magazines and periodicals, among them "The Washington Post, The New York Times," and "The Wall Street Journal".
 He lives in upstate New York.
Deep in the Darkness is the name of a 2004 book by Michael Laimo and a film adaptation by the same name.
 The novel was nominated for a 2004 "Bram Stoker Award for Novel".
 While writing the book Laimo was influenced by the 1973 made-for-television film "Don't Be Afraid of the Dark".
 Laimo wrote a sequel to "Deep in the Darkness" entitled "Return to Darkness", which he released in 2011.
Piercing the Darkness, which was published in 1988, is a sequel to Frank E. Peretti's novel "This Present Darkness".
 It shows contemporary views on angels, demons, prayer and the spiritual realm.
 "Piercing the Darkness" won the ECPA Gold Medallion Book Award for best fiction in 1990.
 The book, along with "This Present Darkness", has been instrumental in promoting belief among Christians in Territorial Spirits.
 They have also increased an interest in spiritual warfare.