A West Bountiful man has been arrested after police say he used "little drug runners" to distribute marijuana and assaulted and robbed a teenager over stolen marijuana.

Preston Anthony Kilpatrick, 18, was booked into the Davis County Jail for investigation of robbery, possession of a controlled substance and arranging the distribution of a controlled substance.

In January, a teenager went to the Layton Police Department with his parents to report that he had been assaulted by Kilpatrick in a Layton park after the teen had stolen marijuana from him, according to a police booking affidavit. Police say Kilpatrick repeatedly struck him in the head before another juvenile also began hitting him and told him to give up his possessions. He also told police that Kilpatrick pointed a "Glock" handgun at his head during the attack.

Police say Kilpatrick and the other attacker took the teen's cell phone before discarding it. The teen suffered swelling and bruising to his head, face and eye due to the attack, the affidavit states.

Investigators later obtained a search warrant for Kilpatrick's Instagram account, where they say they found messages that showed Kilpatrick and two juveniles planning the assault in the Layton park. In additional messages, police allege that Kilpatrick admitted to assaulting the teen and sending a video of the assault to another person. The video shows the victim on the ground before Kilpatrick hits the teen and shows Kilpatrick holding what appears to be a handgun, according to the affidavit.

While searching Kilpatrick's Instagram account, police found a group message that they believe was being used to discuss the sale of drugs. The group was named "pdawg's little drug runners," according to the affidavit. Police say "pdawg" is a nickname Kilpatrick used in his social media accounts.

Police believe Kilpatrick coordinated with teens to sell cartridges of THC, the psychoactive substance found in marijuana. Police noted in the affidavit a deal where Kilpatrick allegedly arranged the sale of THC substances to "a 15-year-old girl he was romantically interested in." Police allege Kilpatrick sold and used the THC with the girl.

Investigators also intercepted new messages to Kilpatrick where one of his underage friends said they need to "kill" an eighth grade student over a drug dealing dispute, according to the affidavit. The exchange led police to believe there could be another assault in the future.

Kilpatrick and two teens were arrested by police on Monday, as he was preparing to sell illicit mushrooms and a THC cartridge to someone in the parking lot of the Layton Hills Mall, the affidavit says.

Kilpatrick allegedly told police that the "Glock" used in the assault was a BB gun.

Kilpatrick is being held in jail without bail, according to booking records. As of Thursday, no formal criminal charges had been filed against him.