Question: When was the murderer who is the subject of Code of a Killer sentenced?

Context paragraphs:
Bankruptcy in the United States: In the United States, bankruptcy is governed by federal law.  The United States Constitution (Article 1, Section 8, Clause 4) authorizes Congress to enact "uniform Laws on the subject of Bankruptcies throughout the United States."  Congress has exercised this authority several times since 1801, most recently by adopting the Bankruptcy Reform Act of 1978, as amended, codified in Title 11 of the United States Code and commonly referred to as the "Bankruptcy Code" ("Code").  The Code has been amended several times since, with the most significant recent changes enacted in 2005 through the Bankruptcy Abuse Prevention and Consumer Protection Act of 2005 (BAPCPA).  Some law relevant to bankruptcy is found in other parts of the United States Code.  For example, bankruptcy crimes are found in Title 18 of the United States Code (Crimes).  Tax implications of bankruptcy are found in Title 26 of the United States Code (Internal Revenue Code), and the creation and jurisdiction of bankruptcy courts are found in Title 28 of the United States Code (Judiciary and Judicial procedure).

Dennis Nilsen: Dennis Andrew Nilsen (born 23 November 1945) is a Scottish serial killer and necrophiliac, also known as the Muswell Hill Murderer and the Kindly Killer, who murdered at least 12 young men in a series of killings committed between 1978 and 1983 in London, England.  Convicted of six counts of murder and two of attempted murder at the Old Bailey, Nilsen was sentenced to life imprisonment on 4 November 1983, with a recommendation that he serve a minimum of 25 years.  He is currently incarcerated at HMP Full Sutton maximum security prison in Full Sutton in the East Riding of Yorkshire, England.

Allan Grimson: Allan Grimson (born 1958) is a convicted British murderer who is responsible for murdering at least two men and is suspected of killing others, possibly up to another 20 undiscovered victims.  The judge, who sentenced him to a minimum term of 22 years at his trial, said that Grimson was a serial killer by nature, but not by number.  Because his two victims were killed on the same date just a year apart (12 December), detectives believe there may be more victims out there as yet unidentified.

George Banks: George Emil Banks (born June 22, 1942) is an American spree killer.  A former Camp Hill prison guard, he shot 13 people to death on September 25, 1982 in Wilkes-Barre, Pennsylvania and Jenkins Township, including seven children - five being his own - their mothers, some of their relatives, and one bystander.  His attorneys argued for the insanity defense, but Banks was convicted of charges including 12 counts of first-degree murder and sentenced to death.  He killed more people in Pennsylvania than any other single mass murderer.

Jack the Ripper: Jack the Ripper is the best-known name for an unidentified serial killer generally believed to have been active in the largely impoverished areas in and around the Whitechapel district of London in 1888.  The name "Jack the Ripper" originated in a letter written by someone claiming to be the murderer that was disseminated in the media.  The letter is widely believed to have been a hoax and may have been written by journalists in an attempt to heighten interest in the story and increase their newspapers' circulation.  In both the criminal case files and contemporary journalistic accounts, the killer was called "the Whitechapel Murderer" and "Leather Apron".

Lucious Boyd: Lucious Boyd (born March 22, 1959) is an American convicted murderer, rapist, and suspected serial killer.  While convicted and sentenced to death for the murder of 21-year-old Dawnia Dacosta, he is a suspect in at least ten other homicides or disappearances.  He was acquitted for the 1993 murder of a man whom he claimed he stabbed in self-defense.

Christopher Scarver: Christopher J. Scarver (born July 6, 1969) is an American convicted murderer who also killed serial killer and cannibal Jeffrey Dahmer at Columbia Correctional Institution, Portage, Wisconsin, in 1994.  Scarver used a 20-inch (51 cm) metal bar he removed from a piece of exercise equipment in the prison weight room to beat Dahmer and another convicted murderer, Jesse Anderson.  Both Dahmer and Anderson died later from their injuries.  Scarver was sentenced to two further life sentences for the killings.

Roger Dale Stafford: Roger Dale Stafford (November 4, 1951 – July 1, 1995) was a convicted spree killer and serial killer sentenced to death and executed for the 1978 Lorenz-Sirloin Stockade murders.

Colin Pitchfork: Colin Pitchfork (born 23 March 1961) is a British convicted murderer and rapist.  He is the first person convicted of a crime based on DNA fingerprinting evidence, and the first to be caught as a result of mass DNA screening.  Pitchfork raped and murdered two girls in Leicestershire, the first in Narborough, in November 1983, and the second in Enderby, in July 1986.  He was arrested on 19 September 1987 and sentenced to life imprisonment on 22 January 1988, after admitting both murders.

Code of a Killer: Code of a Killer is a two-part British police drama television series which tells the true story of Alec Jeffreys' discovery of DNA fingerprinting and its introductory use by Detective David Baker in catching the double murderer Colin Pitchfork.  Filming commenced in late September 2014, and the program aired on the ITV network, on 6 and 13 April 2015.

Supporting paragraphs: Code of a Killer Colin Pitchfork
Answer: 22 January 1988