VISALIA, Calif. (TheBlaze/AP) -- Once Jose Manuel Martinez acknowledged a vast killing spree that included nine people in California, officials set out to decide whether the self-described cartel enforcer actually carried out the horrific crimes.
Details the 53-year-old Martinez provided confirmed his claims. He described with remarkable accuracy the victims' clothes, body positions and the caliber of bullets he fired, investigators said.
"He was spot on almost 100 percent of the time," Tulare County's Assistant Sheriff Scott Logue said.
On Tuesday, a judge in central California accepted a guilty plea from Martinez that will put him behind bars for the rest of his life.
Yet confirming his ties to Mexican drug cartels couldn't be independently determined, Logue said, because Martinez refuses to name them.
However, the presence of Mexican drug cartels in the U.S. is not a new concern.
This graphic previously published by the National Post helps viewers visualize the issue.
"It's not like you can go to a business front door and ask if Jose worked for you," Logue said. "There were whispers for a long time."
Martinez was arrested in 2013, acknowledging a violent career that he said involved more than 30 killings across the country. Martinez will be sentenced next month to life in prison without the possibility of parole under the terms of a plea deal that removes the possibility of the death penalty.
The deal came on the same day a preliminary hearing was set to begin to determine if Martinez would stand trial.
Tulare County District Attorney Tim Ward said prosecutors were pleased about resolving the case. No relatives of victims disagreed with the decision to offer the deal, he said.
Martinez also pleaded guilty to a count of attempted murder of a 17-year-old.
In court, Martinez answered "guilty" to each count read aloud by Judge Brett Alldredge.
Nathan Leedy, an attorney in the county public defender's office who represented Martinez, declined to comment outside of court.
Last year, Martinez pleaded guilty in Alabama to killing a man for making derogatory remarks about Martinez's daughter. He was given a prison sentence of 50 years.
In California, he was charged with killing people in Tulare, Kern and Santa Barbara counties between 1980 and 2011. The victims ranged in age from 22 to 56.
Investigators say that in 1980, Martinez shot a man who was driving to work with three other people in the vehicle. Martinez was accused of shooting another man in bed early one morning in 2000 while the man's four children were home.
Martinez had lived at times in Richgrove, a small farming community in central California about 40 miles north of Bakersfield. He was arrested shortly after crossing the border from Mexico into Arizona and began to disclose details of his past while facing the case in Alabama.
"After he confessed to it, it was just like opening up the floodgate," Tim McWhorter of the Lawrence County Sheriff's Office in Alabama said at the time.
Martinez also is facing two murder charges in Florida.