Casper police on Monday released charging papers filed in support of a first-degree murder charge following a fatal shooting in north Casper early Friday.

Jason Tsosie John, 32, was set to make his initial appearance in Natrona County Circuit Court at 2 p.m. Monday.

According to the affidavit released to news media, officers responded to 1250 N. Center, Space #75 for a reported shooting at 4:12 a.m. Friday. The woman who called police said one man had shot another man inside the trailer, and she had hidden the gun.

Officers arrived and identified 29-year-old Wesley Willow, Jr., on the floor of the trailer. John was also inside.

Officers ordered John to exit the trailer, and then began performing lifesaving measures on Willow. However, Willow was pronounced dead on scene by EMS.

While they were trying to save Willow, officers saw multiple spent rifle shell casings on the floor of the living room. An AR-15/M4 type rifle was located at the foot of a bed in the westernmost bedroom.

While at the scene, John made "numerous excited utterances unsolicited by officers," the affidavit states. Everything John said indicated that he had shot Willow.

A witness later told a detective that he had been with Willow and Willow's girlfriend, when the girlfriend received an upsetting text message from John. Willow then used his girlfriend's phone to call John, asking where John was.

John gave his address to Willow, and Willow said he was going to go to John's residence to fight him. The witness went along.

Willow, the witness and Willow's girlfriend went in Willow's vehicle to the area of John's residence. All three got out of the vehicle and went toward the trailer. As they approached, a flashlight was pointed at them from the porch area of the trailer.

The witness said he did not see a gun or a person on the porch before John and Willow exchanged shouts. The witness said he did not hear anyone indicate that a gun was present.

As Willow was on the porch area, gunshots came from within the trailer and hit Willow, who fell into the trailer. The front door of the trailer was open during the entire incident, the witness said.

Willow's girlfriend told police that shots were fired before Willow went up the steps to the trailer. She and the witness took cover at the side of the trailer, and Willow fell into the open front door.

John's mother told police that she had been staying with John and went to sleep in her bed in the westernmost bedroom. She awoke to the sound of gunshots, and went into the living room to see John holding a rifle, standing over Willow's body.

John provided a statement to police through his attorneys. He said he was at home when Willow called, and he hung up. Willow continued to call, and John finally answered. Willow then told John that he was coming to assault him.

Per John's statement to police as recorded in the affidavit, John waited at home until he heard car doors open and shut, then he went onto the porch to investigate. John saw Willow and the two others approaching his trailer.

John shone the light mounted to the foregrip of his rifle at the trio and told them stay away. John went back into his house and shut the door before Willow opened the front door and went inside, "coming at" John. John then shot Willow.

Police describe John as standing 6'4" tall and weighing 275 pounds. Willow was 5'7" and weighed 160 pounds.

Multiple empty shell casings were recovered from the scene, and multiple entry wounds were found to the front and back of Willow. Bullet holes penetrated Willow at an upward angle, police say, despite the height difference between he and John.

Three bullet holes were found in the floor where Willow's body had been found. The angle of those gunshots was nearly perpendicular to the floor and originated from almost the same point; evidence technicians said the trajectories were consistent with a person firing from a standing position directly down into a target above which the shooter was standing.

A search warrant allowed police to observe text messages exchanged that morning between John and Willow's girlfriend. One text from John read, "I'll blow you away just like Wesley and Will. To protect [redacted] and [redacted] and [redacted]. F--- yeah! Test me b----! Come at me! My kids are my life!"

One minute later, John texted, "I don't f--- around!!!"

The next minute, a call was placed to John's phone from the phone of Willow's girlfriend. Then, between 4:02 a.m. and 4:06 a.m., John sent a series of texts which read:

"Where you at b----?"

"I'm waiting m-----f-----!!!"

"That's what I thought m-----f-----. You a b----"

"F--- you! F--- (Name) that ho! F--- all y'all"

"I'm ready!"

None of those texts received a response from Willow's girlfriend's phone or anyone using it.

The investigating detective believes probable cause exists to show that John "purposefully shot and killed [Willow] and he did so with premediation and planning."

No booking photo of John was available on Monday.