A Texas national guard member assigned to a border security mission helmed by the state’s governor, Greg Abbott, died this week at his unit’s hotel, leaving him as the latest of several soldiers to die while deployed on the controversial operation.

Alex Rios Rodriguez, a 52-year-old sergeant, suffered a medical emergency from which first responders were unable to revive him while he was at his quarters in McAllen, Texas, said a news release Friday issued by officials with the agency that runs the state’s national guard.

Those officials said Rios’s death was not considered to be directly related to Operation Lone Star. But, according to a report in the Army Times, Rios is at least the eighth Texas national guard soldier linked to Operation Lone Star to die since Abbott increased the number of deployments to the mission with thousands of involuntary call-ups last fall.

Four guard members who were either sent to the border or tapped to deploy there died by suicide between October and December last year, the Army Times’ report said. Two more died in a pair of separate accidental shootings reported in January and February. And in April, a 22-year-old soldier named Bishop Evans drowned while trying to save two people he believed were struggling to swim across the Rio Grande.

About two months before the death of Evans, who earned a posthumous promotion to sergeant, those running Texas’ national guard had ordered rescue ropes and hundreds of ring buoys to aid in water rescues. But when Evans died, most of the state national guard’s members had not received that equipment, the Army Times reported.

Operation Lone Star costs an estimated $2.5m weekly, and earlier this month Abbott announced the state would spend an additional $30m on the mission to provide grants to local governments to ostensibly limit crime along the border.

Abbott launched the operation in March 2021 as a response to a reported increase in US-Mexico border crossings. The governor declared the higher number of border crossings a disaster, enabling him to send his state’s national guard there.

Authorities have since touted the arrests of more than 274,000 migrants on nearly 17,000 criminal charges. But the mission has drawn criticism because those arrests include ones that are physically distant from the border, not related to crimes there, and made by law enforcement agencies not directly participating in Operation Lone Star, according to reporting from the Texas Tribune, ProPublica and the Marshall Project.

There were reports earlier this month that the operation is also under investigation by the federal justice department for potential civil rights violations. News of the investigation came days after 53 migrants who were being smuggled across the border in a sweltering tractor-trailer were found dead in the back of the vehicle in San Antonio.

Rios, the soldier who died Thursday, was a team leader for Delta Company in the 536th Brigade Support Battalion, officials said.

“Our sincere condolences go out to the family of Sgt Rios Rodriguez,” the Texas national guard’s leader, major general Thomas Suelzer, said in a statement. “Our thoughts and prayers are with them at this difficult time.”