Outside his regular job as a stock clerk at Super 1 Foods in Lafayette, Christian Roper had another idea to make money.

The 18-year-old who once had an interest in emergency medicine but a problem with the sight of blood planned a robbery in the parking lot of his girlfriend's apartment complex off Kaliste Saloom, police said in court filings.

He had a target in mind, someone he expected would have enough money and merchandise to make it worth his while. His weapon: an airsoft gun, which looks real but is not a firearm.

Roper's idea was to pull his phony gun on a drug dealer, take what he could and run for it. He'd done it once before, one of his friends told police.

So he set up a buy. He said he needed 2 ounces of marijuana and asked to meet the dealer in the parking lot. It's where he told his girlfriend he liked to do drug deals.

Roper convinced two friends to help him. Ayden McDonald, 18, drove his tan Buick to pick up 20-year-old Trevis Thomas, who bought his own toy gun at Walmart to help Roper to carry out the robbery.

But something didn't sound right to Derek Junca, the dealer Roper called for the marijuana, police said.

Just days earlier, Roper called Junca asking to buy some pot, and wanted to meet by an apartment pool to do the deal. Junca didn't feel right about it, so he drove off after arriving at the complex without making the sale, police said.

This time after Roper called again asking to buy pot, Junca asked a friend to go with him to make the deal. Tyler Hebert agreed to ride along, and brought what police believe was a Smith & Wesson compact 9-mm pistol with him.

Hebert drove Junca's silver 2010 Ford F-150 so Junca could handle the deal from the passenger's side. They pulled in to the Grand Point Apartments just before 10 p.m.

But the robbery went bad.

Roper saw the truck pull into the gated apartment complex. After it pulled up near him, Roper made his move and hopped into the backseat on the passenger side behind Junca.

Roper started hitting Junca in the back of the head and the two struggled with a handgun sitting on Junca's lap, police said.

Roper's two friends were nearby, McDonald still in the car and Thomas playing lookout.

That's when Hebert, sitting in the driver's seat, pulled his gun and shot, police said. It only took one shot to stop Roper. The bullet hit him in the neck. Police said they know Roper was shot in the truck because that's where they found splatters of his blood.

Roper's friends rushed off after the shot was fired, police said.

As the pickup truck sped away, Roper ended up on the hard parking lot concrete. A man driving into the complex saw what he thought was a trash bag in the middle of the parking lot, but realized it was a man bleeding and convulsing.

It was Roper. The driver called 911.

Police arrived later to find Roper in a pool of blood in the parking lot, his airsoft gun nearby. He was pronounced dead there.

After Junca and Hebert left the apartment complex, the two drove to a gas station where they disposed of a shell casing, Junca told detectives. Then they drove to a friend’s house.

There, Hebert, whose shirt was bloody, used towels to wipe Roper's blood off the backseat of Junca's truck, police said. The towels were burned in a fire pit later.

Hebert, known on the street as Gram, wanted people to know he took care of Roper. After the shooting, Hebert made a Snapchat call to a friend of Roper's in Michigan — "Ya boy just tried to rob me out of two zips. They punched my dude in the passenger seat. And I just turned around and shot," the message said, according to police.

When Junca and Hebert talked the day after the shooting, Hebert said he threw his gun in some water while he drove to his mother's house in New Iberia, Junca told police. Junca cleaned the truck and scraped stickers off its back windshield to make it more difficult for police to match possible witness descriptions of an F-150 speeding away from the complex the night before.

Hebert left town in a rental car days later for his apartment in Aurora, Colorado. He took his mother and girlfriend with him. It's where he was arrested.

Detectives offered the account of Roper's March death in a 13-page court filing, compiled after interviews with witnesses and defendants in the case.

Hebert, 27, and Junca, 21, face first-degree murder charges. McDonald and Thomas face attempted first-degree robbery charges.

All four have pleaded not guilty.

Hebert’s trial is scheduled to begin Jan. 13. McDonald, Thomas and Junca have pre-trial hearings scheduled in the coming months.

Contact Ashley White at adwhite@theadvertiser.com or on Twitter @AshleyyDi.