Elizabeth Lloyd King was born in Plymouth, Massachusetts, in 1847. She grew up in a respectable family, the daughter of Isaac B. King and Harriet A. Hoyt. By all accounts, she had a normal childhood, and her mother recalled she was modest and polite.

However, as she grew older, she began to exhibit erratic and troubling behaviors. Her moods became unstable and her speech incoherent at times. In 1867, she was committed to Taunton Lunatic Asylum under the alias Alice Howard. Doctors diagnosed her with mania caused by "some disease peculiar to females." She was discharged later that year after appearing improved.

Over the following years, Elizabeth lived a transient life, working as a milliner and teacher in several northeastern cities including New York, Philadelphia, and Hartford. She took on many aliases and kept her movements obscure.

In 1872, using the name Kate Stoddard, she met Charles Goodrich, a widowed businessman in Brooklyn. Their relationship quickly grew intense. She claimed they were married in a ceremony officiated by a man she later discovered was not a clergyman. When Goodrich tried to end the affair, she became desperate to maintain their bond.

On March 20, 1873, in the brownstone house Goodrich had built for himself in Brooklyn, Elizabeth confronted him for the last time. During a heated argument in the basement, she shot him three times in the head. She tried to stage the scene, dragging his body near the fireplace and cleaning up the blood.

At first, police suspected suicide or an unknown burglar. But her letters—signed variously as Amy, Kate, and Amy G.—soon revealed her involvement. Elizabeth fled and hid under the name Minnie Waltham in Brooklyn boarding houses for nearly four months, all while continuing to work making bonnets.

She was finally caught on July 8, 1873, by Mary Handley, a friend turned police informant who spotted her boarding the Fulton Ferry. Once arrested, she calmly confessed to being Kate Stoddard and admitted the killing.

Her inquest drew huge crowds, fascinated by a story that combined deceit, mental illness, and violence. Newspapers called it the "murder of the decade."

In July 1874, after more than a year in jail, a court-appointed medical panel ruled that she was insane and unfit to stand trial. She was committed for life to the State Lunatic Asylum in Auburn, New York. There, she continued to follow news about herself and corresponded with officials, even sending an elaborately constructed letter protesting her confinement.