When the body of Vincente Huerta was found in a field off Fischer Road on Aug. 24, 2007, circumstances surrounding his death were a mystery.

All police knew that he had been shot in the head and his SUV was reported stolen.

In August 2010, Bexar County Sheriff’s Department cold case detectives got a break.

They took Vanessa Tunchez, 21, into custody for questioning.

“They were saying that fingers were pointing that I did it. That I shot a guy or I shot somebody,” Tunchez testified on Wednesday.

She was testifying as a state’s witness in the murder trial of Aaron Alaniz (pictured).

Tunchez said that a plan to do a carjacking was developed in her apartment in the summer of 2007. But she insisted she did not take part in the carjacking.

Alaniz and several friends -- using a teenage girl as a decoy -- carjacked Huerta and, in the process, shot him in the head.

During his trial on Wednesday, Aalaniz’s attorneys suggested that Tunchez’s testimony was unreliable.

She admitted she had been arrested multiple times for shoplifting, and once on prostitution charges. And Tunchez said that she used drugs.

“Do I use heroin?’ she said. “I do sometimes.”

Though he was indicted on capital murder charges, Alaniz is on trial for first-degree murder.

The reason that he was not tried for capital murder is tied to a Supreme Court ruling.

Alaniz was 16 years old at the time and the Supreme Court says that a jury must have options besides the death penalty or life without parole in deciding punishment in juvenile cases.

Testimony will continue on Thursday in Judge Angus McGinty’s 144th District Court.