FRESNO, Calif. - A suspected contract killer charged with killing nine people in three California counties over several decades is being investigated in connection with other unsolved slayings, according to sheriff's officials.

Jose Manuel Martinez, 51, targeted victims in Tulare, Kern, and Santa Barbara counties between 1980 and 2011, Tulare County Assistant District Attorney Anthony Fultz said. He was charged with the nine slayings on Tuesday.

Martinez has lived on and off in Richgrove, a small farming community in central California about 40 miles north of Bakersfield. He's now being held in Alabama, awaiting trial for a 2013 slaying, and Fultz said he's also wanted in Florida on suspicion of two killings there in 2006.

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Tulare County Sheriff Mike Boudreaux told the Fresno Bee, that investigators are trying to determine whether Martinez is a suspect in local unsolved murders.

Attorney Michael Terry, who has represented Martinez in Alabama, did not immediately respond to a telephone message or email Tuesday evening.

The California charges would make Martinez eligible for a death sentence, if he is convicted.

Fultz declined to say who investigators believe paid Martinez. Six of the victims were killed in Tulare County, two in Kern and one in Santa Barbara. They ranged in age from 22 to 56, investigators said.

Investigators had long sought answers to the slayings, and they received key information from Alabama authorities shortly after Martinez was arrested in June 2013, Fultz said. Tulare County detectives have visited Alabama three times since, according to the prosecutor.

"They were able to then piece together the various murder cases we have filed," he said.

In addition to the nine murder counts, Martinez was charged in California with one count of attempted murder and the special circumstances of committing multiple murders, lying in wait, kidnapping, and murder for financial gain.

Fultz said authorities from the other California counties agreed to have Martinez tried in Tulare County.

Acting Tulare County Sheriff Mike Boudreaux said in a news conference that the case is far from completed.

"While this case has been filed, there is plenty of work to be done," he said.