It's unlikely that a Syrian guard was trying to kill the U.S. Marine he shot in the leg in a Feb. 17 incident at a joint, coalition-Syrian outpost in the Middle Euphrates River Valley, according to an Operational Inherent Resolve investigation.

U.S. Central Command on Thursday afternoon released a highly redacted report on the AR 15-6 investigation into the suspected "green on blue incident," which resulted in Marine Sgt. Cameron Halkovich being shot twice in the left leg.

Halkovich and Cpl. Kane Downey were making a nighttime check of the base perimeter when a Syrian Democratic Forces guard shot Halkovich with his AK-47, according to a story first reported by Task and Purpose.

Downey immediately returned fire, killing the guard at close range.

The 15-6 investigation, led by an unnamed Marine colonel, determined that the shooting was an "isolated incident" and that Downey "acted appropriately and proportionally to the threat and the situation."

"However, I cannot determine conclusively if [Halkovich] was shot intentionally by the [SDF] guard, or if he shot as a result of a negligent discharge," the report states.

The SDF guard was "approximately 4 feet away" from Halkovich, who was not wearing body armor inside the security perimeter, the report states.

"Had the [SDF] guard intended to kill [Halkovich], it would have been exceedingly easy for him to do so at that distance," according to the report.

Before the shooting occurred, Halkovich neared a Mine-Resistant Ambush Protected, or MRAP, vehicle at a defensive position and was approached by the SDF guard, according to the investigation.

The SDF guard offered a cigarette. Halkovich "greeted the [SDF] guard but declined the cigarette, and reports possibly shaking the [SDF] guard's hand before turning east and walking towards the MRAP," the report states.

"At this point [Halkovich] was shot in the back of his left leg by the [SDF] guard and immediately fell to the ground," according to the report.

Downey "heard the shots and turned to see the [SDF] guard's weapon (AK-47) in his shoulder and pointed towards [Halkovich]; he further reports that the [SDF] guard oriented the AK-47 on him," the report states.

Downey told investigators he was "feeling threatened, believed [Halkovich] was dead, and immediately engaged the [SDF] guard with two shots to the chest from less than 15 feet away," the report states.

It was over in a "matter of seconds," the report continues, describing how Downey "immediately kicked away the [SDF] guard's weapon, confirmed he was no longer a threat, began treating [Halkovich's] injuries by applying a tourniquet, verbally directed the Marine Guard in the MRAP to radio the situation, and then fireman-carried [Halkovich] to the [Forward Surgical Team] approximately 100 meters away."

Halkovich received a Purple Heart for his injuries. Downey was awarded a Joint Service Commendation Medal for what the investigation described as his "heroic actions" during the incident.

The SDF conducted its own investigation and found this to be an isolated incident as the result of a negligent discharge, but "fully accept" that the Downey's reaction was "appropriate and justified given the situation and conditions," according to the report.

The SDF investigation maintains that the rounds fired from the SDF guard's weapon "hit the ground and ricocheted into [Halkovich's] leg," the report states.

The 15-6, however, said medical examination showed that the "wounds are clearly indicative of direct entry of two 7.62mm rounds and not a ricochet."

The 15-6 investigation also found that the SDF guard "likely had a round chambered in violation of the weapons status policy," which was set at "weapons condition 3 (magazine inserted, no round in the chamber)."

If it was not a negligent discharge, there was "insufficient evidence" to show why the SDF guard would have wanted to shoot Halkovich, the report states.

There were, however, two "unrelated" negative interactions between SDF and U.S. personnel before the Feb. 17 incident, according to the report.

"There was an incident where an [SDF] guard chambered a round and approached a Marine while on post," the report states. "U.S. personnel involved related that the situation was de-escalated quickly and was not a significant concern. The [SDF] soldier involved in this incident was not the same [SDF] ... guard killed on 17 February 2018."

Another incident occurred "on or about Feb. 15," when SDF guards did not want to allow a vehicle with wounded civilians to enter the base to receive medical treatment ... but U.S. forces interjected and allowed the civilians to be treated at the FST," the report states.

Despite these incidents, an examination of the SDF guard's phone found no proof that he wanted to harm Halkovich, the report states.

"Nothing discovered ... indicated there was a plot to commit the attack or a connection to ISIS influence," according to the report.

The 15-6 maintains that "it is unlikely that any further investigation is going to reveal the true motive of the deceased [SDF] guard's actions" and warns that such incidents are likely to occur in the future.

"While it appears this was an isolated incident, it doesn't change the realities of operating with partners in a complex and hostile environment," the report states. "As the conflict progresses, tensions and patience will deteriorate; therefore it is important that leadership continue to reiterate vigilance and the potential of future incidents."

-- Matthew Cox can be reached at matthew.cox@military.com.