While filming courtroom scenes, the location was hit by the 6.7 Northridge, California, earthquake. Kevin Bacon was handcuffed to a large table, he took refuge underneath, while an enormous crystal chandelier swung overhead. The warehouse studio was later condemned.
In real-life, Henri Young's defense was handled by two prominent San Francisco attorneys, Sol A. Abrams and James Martin MacInnes. They offered the temporary insanity defense, saying that Young's brutal treatment on Alcatraz had led him to murder his fellow inmate, Rufus McCain. The jury bought the argument, and returned a verdict of Involuntary Manslaughter, largely because the Alcatraz officials who testified at Young's trial refused to provide any actual details of prisoner treatment at the prison to contradict Young's defense. (Alcatraz officials and guards lived under strict rules not to talk about prison procedures when off the island, for fear these details would make it into the newspapers and be used by criminals in breakout attempts.)
According to Stephen Tobolowsky, Oliver Stone was originally cast as Mr. Henkin, but did not show up on the day of filming. Mark Rocco called Tobolowsky to take over the role just a few hours before shooting.
The warden in the film, James Humson, is based on Warden James A. Johnston, who served as warden of Alcatraz from 1934 to 1948. Far from being a befuddled bureaucrat, Warden Johnston was very much in charge during his tenure on Alcatraz. Johnston had previously served as warden of both San Quentin and Folsom Prisons prior to his appointment to Alcatraz, but he did not (as depicted in the film) serve as warden for all three prisons simultaneously. (This would have been impossible, because Alcatraz was a federal prison, and San Quentin and Folsom are both state prisons.)
In an extract for Murder in the First (1995), from a CINEFILE in the 2006 fourteenth edition of Time Out, critic and film historian Geoffrey Macnab wrote: "The film is loosely based on a true story, but director Marc Rocco has taken huge liberties with the subject matter. Young was not the innocent country boy portrayed here. Nor were the warders quite as barbaric as Rocco suggests. (In one shocking scene, we see Warden Glenn slash Young's Achilles tendon with a razor to ensure that he'll never again try to escape.) The claims that Young's case precipitated the closure of Alcatraz don't add up either. The teenager was tried in 1941, 20 years before the prison was shut down. As a protest film, Murder in the First is over 30 years too late. None the less, this is a riveting courtroom drama, buoyed by intensely committed performances from former Bratpack stars, Slater and Bacon". Kevin Bacon played Henri Young imprisoned in Alcatraz, Gary Oldman played the brutally sadistic warden Milton Glenn and Christian Slater played Young's lawyer James Stamphill.
The trivia item below may give away important plot points.
The real Henri Young remained at Alcatraz until 1948, when he was transferred to the Medical Center for Federal Prisoners at Springfield, Missouri. When his Federal sentence expired in 1954, he was turned over to the Washington State Penitentiary at Walla Walla to begin a life sentence for an earlier murder conviction. In 1972, at the age of 61, Young was released from Washington State Penitentiary, but he jumped parole and, according to Washington State authorities, his whereabouts are unknown.