FORT SMITH — No criminal charges will be filed by the Sebastian County Prosecuting Attorney’s office in the case of an Arkansas National Guard soldier who died in June during training at Fort Chaffee.

Sgt. Sylvester B. Cline, 32, of Pine Bluff died June 14 at Mercy Hospital in Fort Smith after suffering from “environmental hyperthermia,” according to the state medical examiner’s opinion released in a report by Sebastian County Prosecuting Attorney Daniel Shue on Wednesday.

“It is the opinion of this office that no criminal charges can be filed against any person with regard to this unfortunate death,” Shue wrote in the report to Cpl. Patrick A. Schmidt of the Arkansas State Police.

Cline was a maintenance worker in Pine Bluff and is survived by four children and other family members, according to a previous Times Record report.

Cline was manning a .50 caliber machine gun on a tripod with Sgt. Calvin Neal that day in mid-June with temperatures and high humidity pushing the heat index to 105. Cline and Neal’s position offered them no cover from the sun, and Cline had left his “personal hydration system” in one of the transport trucks, the report noted. Cline and Neal shared a hydration pack and then later Cline retrieved his pack from the truck, the report adds.

Cline and his unit started the day with a 5:30 a.m. ride to Range 100 where they ate breakfast and conducted a safety briefing before their training exercises. Between 8-9 a.m. a 400-gallon “water buffalo,” or portable drinking water carrier, was brought up to the firing line to help with hydration, the report added.

Second Lt. Daniel J. Baum told investigators there were breaks built into the training and two ambulances were on the scene with six medics. Two ice dumps were also brought in during the training day, Baum told investigators.

“Sgt. Neal observed Sgt. Cline to be sweating a lot, as was everyone; he also noted that Sgt. Cline was hydrating throughout this time,” Shue’s letter states. “Sometime after lunch, Sgt. Cline began to have cramps in his legs and took a couple of breaks in a nearby shaded area.”

At 4:15 p.m. Cline walked to the ambulance and his conditioned worsened, Shue notes. Cline’s mental state began to falter and by 5:15 p.m. he was still able to talk but could no longer walk. At 5:40 p.m. medics began CPR and Cline was medically evacuated by helicopter to Mercy Fort Smith. He arrived at about 6 p.m. and CPR efforts were not able to revive him. Cline was pronounced dead at 6:17 p.m.

There were five “heat casualties that day,” Shue’s report added. More than 1,300 soldiers from Arkansas’ 39th Infantry Brigade Combat Team were training at Fort Chaffee.