An 18-year-old U.S. Army soldier was the triggerman in a paid hit on a Mexican drug cartel figure who was also an informant for the U.S. drug enforcement agency, police said Tuesday in announcing the arrests of the soldier and two alleged coconspirators.

Pfc. Michael Jackson Apodaca, who was based at Fort Bliss near El Paso, told El Paso police investigators that he fired the shots in the May 15 slaying of Jose Daniel Gonzalez Galeana, police said in charging documents. Gonzalez, a lieutenant in the Juarez drug cartel, was shot eight times outside his pricey El Paso home.

Apodaca, Christopher Duran, 17, and Ruben Rodriguez Dorado, 30, were arrested Monday and charged with capital murder in Gonzalez's slaying. Each was being held on $1 million bond. It was not immediately clear if Apodaca or Duran had retained lawyers. Online court documents didn't list attorneys for any of the three men, and police said they didn't know.

A woman at Rodriguez's house who declined to give her name but said she was his wife, said she couldn't comment on the charges and referred questions to a lawyer, Russell M. Aboud. Aboud did not immediately respond to a phone message Tuesday seeking comment.

According to the charging documents, the Juarez cartel wanted Gonzalez killed because they believed he was a government informant or had changed his allegiance to a rival cartel, and had provided information to authorities that led to the arrest of a more senior cartel member.

Gonzalez was in fact an informant for the U.S. Immigration and Customs Enforcement agency, according to three U.S. officials who spoke on condition of anonymity because they were not authorized to speak about it.

Investigators said Rodriguez told them Monday that like Gonzalez, he was a midlevel member of the Juarez cartel, which he referred to as the "Compania." He said his job was to coordinate surveillance by "following intended victims up until their execution in Mexico," and that he had been ordered to track down Gonzalez, according to the charging documents.

Gonzalez, who apparently ran a freight company from his two-story home, was aware Rodriguez was looking for him and told a witness he would be killed if Rodriguez found him, police said.

Rodriguez, Apodaca and Duran tracked down Gonzalez at a relative's home in nearby Canutillo, followed him home and killed him, investigators said.

A witness reported hearing an argument in Spanish just before the shooting, police said.

Duran told investigators he drove the getaway car after Apodaca shot Gonzalez, police said. Both he and Apodaca said they had been paid to take part in the killing, police said.

Additional arrests are expected.

Details of Apodaca's military service were not immediately available. A Fort Bliss spokeswoman, Jean Offutt, declined to discuss the specifics of Apodaca's case.

"Anytime someone does something like this, and a soldier in our case, it's terrible," Offutt said.

It's not the first time the three men have gotten in trouble with the law.

All three men and a 16-year-old boy were arrested in May and charged with trying to steal a truckload of televisions from an El Paso dealership, Cazador Logistics.

Sheriff's deputies said the four tried to hook a 53-foot trailer containing the televisions onto one of two sport utility vehicles but were unsuccessful and fled. They were arrested a short time later on a highway east of the city.

The 16-year-old's name was withheld because he was treated as a juvenile.

It was not immediately clear how the other three pleaded in that case.