From 1800s: 9 year old and 5 year old girls kill 7 year old boy in plot

While television series devoted to “killer children” fight for ratings, children who murder are not new phenomena. A crime reported in Richmond, Virginia, in the mid-1980s proves that children had committed murder long before they became headlines.
An article in the 1885 issue of The Streator Free Press headlined “Precocious Depravity” gives the details of one such crime. Around March 25, 1885, in Scottsville, a nine-year-old child confessed to killing her seven-year-old cousin by forcing him to hang himself and then beating him with a shovel. Her five-year-old sister, who was present and witnessed the entire incident, assisted in the murder and admitted the crime.
Melville Barrett and Mary Cooper lived with their uncle David Cooper in a cabin in Albemarle County.
The Streator Free Press  (03-28-85)
Mary became enraged at Melville “for eating her egg.” In retaliation, Mary and her little sister hatched a plan of revenge. First, they asked Melville to “get on a chair” so he could attach a rope to a beam in the cabin ceiling; they wanted to “put up a swing.” (Several reports have them tying the rope to the ceiling of an outhouse, listing Mary as eight.) Details are not given; somehow, Mary made a loop at the end of the rope. The younger sister persuaded Melville to put his head through the loop. “Then (Mary) knocked the chair from under him and struck him several severe blows over the head with a shovel” (P.8), killing Melville.

Uncle David Cooper was the police’s suspect and taken to jail, but from the onset of the crime, the five-year-old girl calmly confessed. Both girls appeared before the grand jury, and each told the same story about the murder.
The crime was one of several reported by The Chicago Tribune as “sometimes trivial and even grotesque, and go to show how cheaply human life is considered” (1886, p. 14).
The crime never made headlines. When it appeared on page one, it was never a top story. The fate of Mary Cooper and her sister are lost to time; the case failed to make news after the girl’s testifying before the grand jury. No photographs or sketches accompany and of the articles. Little Mary Cooper and her sister are two child murderers of so many that appear in the history books of crime.

“A Child Murderess.” (March 27, 1885). The Daily Review. Decatur, Illinois. P. 1.
“A Young Murderess.” (April 2, 1885). The Norfolk Landmark. Norfolk, Virginia. P.3.
“An Eight-Year-Old Girl Confesses.” (March 26, 1885).  The Wilkes-Barre News. Wilkes-Barre, Pennsylvania. P. 3.
“An Eight-Year-Old Girl Confesses To Murdering Her Cousin.” (March 25, 1885). The York Dispatch. York, Pennsylvania. P.1.
“Murders.” (January 1, 1886). The Chicago Tribune. Chicago, Illinois. P. 14.
“Precocious Depravity” (March 28,1885). The Streator Free Press. Streator, Illinois. P. 8.