By SCOTT SMITH

FRESNO, Calif. (AP) -- 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 across the country, according to prosecutors.

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 in a 2013 slaying, and Fultz said he's also wanted in Florida on suspicion of two killings there in 2006.

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

Fultz said he is confident Martinez committed at least the nine killings he's charged with, but he has heard figures as high as 30 from across the nation.

"We're actually not sure what the full scope is," Fultz said. "It will depend upon what the investigation shows."

Fultz declined to comment on any connection Martinez may have had with drug cartels, saying he did not want to damage the case at this early stage. Fultz said that too will remain under investigation.

Acting Tulare County Sheriff Mike Boudreaux said his deputies came in contact with Martinez investigating a rash of home invasion robberies in late 2012 and early 2013. Martinez was at a home searched and questioned by Sgt. Christal Derington, but not considered a suspect.

Attorney Michael Terry, who has represented Martinez in Alabama, declined to comment Wednesday in an email message.

Investigators have released some details of their case, saying 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.

One man was shot dead in 1980 driving to work in the morning, while two men were shot in 1982 working on a ranch, one surviving. The same year, another man went missing before being found two days later by ranchers shot and stabbed to death. Yet another was found in 2000 shot to death in bed with his four children at home.

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, including Sgt. Derington, have visited Alabama three times since, the prosecutor said.

"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.

Of the nine, four murder charges include the allegation he committed the crime for financial gain, the criminal complaint says.

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

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.