Background: The 1200 block of Bliss Drive in Bellefontaine Neighbors, Missouri (Google Maps). Inset: Craig Jones (St. Louis County Police Department).

A man had a sinister plan to kill someone for about a week before bludgeoning his sister with a dumbbell and then stabbing her to death, Missouri authorities claim.

Craig Jones, 22, has been charged with first-degree murder and armed criminal action in the death of Taylar Hill, court records show. The harrowing scene unfolded Tuesday evening at a home in the suburbs of St. Louis.

Jones and his sister were at a home on the 1200 block of Bliss Drive in the city of Bellefontaine Neighbors on Tuesday evening when Jones hit her with a seven-pound dumbbell “several times on the head,” according to a criminal complaint reviewed by Law&Crime. He then allegedly “retrieved a steak knife and stabbed the victim” several times.

Jones is said to have “fled” from the residence. Police officers arrived at the home just after 8 p.m. after being contacted about a stabbing, according to the Bellefontaine Neighbors Police Department. They reported her as suffering from “life-threatening stab wounds,” and though she was transported to a local hospital, she was pronounced dead.

Local CBS affiliate KMOV reported that Hill was 26 years old.

The St. Louis County Police Department took control of the investigation at the request of the Bellefontaine Neighbors Police Department. Jones was later found by police and “taken into custody without incident,” the criminal complaint states.

He then reportedly shared a shocking admission of guilt.

Jones “confessed to police that he murdered his sister and had been planning on killing someone for approximately a week,” according to the court document.

He “intentionally killed his unarmed sister without provocation,” the complaint added.

Jones was scheduled to be arraigned on Thursday.