Short answers, pulled from the story.
Song Ci, a Chinese director of justice, wrote the first book on forensic science. Xi Yuan Lu, translated as Washing Away of Wrongs, was written in 1248 during the Song dynasty. It described methods for determining cause of death, protecting evidence, and distinguishing murder from suicide or accident.
James Marsh developed the Marsh test after being frustrated by an acquittal in an 1832 murder trial. He first described the test in The Edinburgh Philosophical Journal in 1836. The method was sensitive enough to detect as little as one-fiftieth of a milligram of arsenic.
Sir Alec Jeffreys applied DNA analysis to a criminal case for the first time in 1985, in the investigation of the murder of Lynda Mann in Narborough, Leicestershire. The case ultimately led to the arrest of Colin Pitchfork in 1987 and to the creation of searchable DNA databases.
Azizul Haque and Hem Chandra Bose, two Indian fingerprint experts working in the Calcutta Anthropometric Bureau, developed the primary classification system. The system was named after their supervisor, Sir Edward Richard Henry, and was adopted when the first United Kingdom Fingerprint Bureau opened at Scotland Yard in 1901.
Locard's exchange principle, formulated by Dr. Edmond Locard, states that every contact leaves a trace. Locard founded what may have been the first criminal laboratory in the world in Lyon, France, in 1910, after persuading the Police Department to give him two attic rooms and two assistants.
According to the Innocence Project and the US Department of Justice, forensic science errors contributed to approximately 39 to 46 percent of wrongful convictions. The National Academy of Sciences has noted that many traditional forensic science techniques were never empirically validated, and that all examiners are subject to confirmation bias.