Cole County prosecutors filed charges of conspiracy to commit robbery against: Mark Cavin III, 18; Kendra Sanchez, 17; Marqukis Hayes, 17; and Isiah Alexander, 17. The charge is a Class B felony that could result in prison sentences of five to 15 years.
Jefferson City police said the four had planned to rob the victim at a residence in the 1700 block of West McCarty Street.
The statements also indicate at least one other person was involved, but he was not named and has not been charged.
The statements said Cavin brought a plastic gun and a black ski mask to the robbery, and that he was to be a lookout while the others robbed the victim.
Sanchez told police she was to go to the front door and get the victim to open it, and then she was to open the back door so the boys could go into the house and rob the victim.
Alexander said he was to "knock out" the victim, if needed.
Police said Hayes admitted to helping plan the robbery and carrying a gun to scare the victim, and planned on using it once they had gotten inside the house.
None of the police reports reveal how officers identified the suspects, or how they found and arrested the four teens.
The grand jury also indicted four people taken into custody after four drug search warrants were issued earlier this month in Cole County.
Melissa Faulkner, 32, and Walter Carlson, 26, both of 4213 Crim Court, are each charged with possession of methamphetamine and unlawful use of drug paraphernalia.
Probable cause statements show authorities seized several resealable bags with drugs, including crystal meth.
Surveillance equipment which monitored the rear exterior of the residence and the residence's living room were seized.
Richard Pitts, 47, of 5605 Heritage Highway, was charged with two counts of possession of a controlled substance with intent to distribute.
A probable cause statement showed authorities found two bags of marijuana and a bag of methamphetamine in a safe in Pitts' home along with four digital scales.
They also seized more than $500.
Stephen Jackson III , 43, of 5605 Heritage Highway, was charged with possession of marijuana and unlawful use of drug paraphernalia.
Six packaged bags of marijuana were found in his home along with an electronic scale, according to a probable cause statement.
The grand jury also indicted a Jefferson City man who was charged with second-degree statutory rape and forcible rape for an incident that occurred in July 2012.
According to a Cole County Sheriff's Department probable cause statement, Clifton Hopper, 24, is believed to have committed the crime in the 200 block of Little Creek.
The victim was 16 when she claims Hopper forced her to have sex.
Hopper told investigators the two did have sex, but that it was consensual and he thought she was older.
Also indicted by the grand jury was a Jefferson City man who fled from police officers in December 2012, then fought with them while being taken into custody.
Maurice Rollins, 26, is facing charges of possession of heroin with intent to distribute, assault on a law enforcement officer and resisting arrest.
According to police reports, Jefferson City Community Action Team officers attempted to stop a suspicious vehicle in the area of West Main and Berry streets.
Upon stopping the vehicle, the passenger, Rollins , quickly exited and approached officers.
When questioned, Rollins initially began to walk away, then ran from officers despite orders to stop.
A foot chase ensued, and officers caught Rollins in an alley between Brooks and Berry streets.
Rollins then struck and punched officers, but was eventually taken into custody.
A search of Rollins revealed he was carrying nearly a half of a gram of heroin that had been packaged for sale.