A man charged with murdering nine people in California has told authorities that he has killed up to 40 people.

Jose Manuel Martinez (51) told investigators he carried out the crimes working as an enforcer for a Mexican drug cartel, Errek Jett, a district attorney in Lawrence County, Alabama, said.

Mr Jett said prosecutors believed Mr Martinez because of the details he gave.

He was charged on Tuesday with nine murders in a killing spree spanning three decades in California, central California officials said. He could face the death penalty if convicted.

He was also charged with attempted murder, kidnapping and murder for financial gain.

Mr Martinez allegedly shot a 56-year-old man in his bed in 2000 and dumped at least three bullet-ridden bodies in orange groves in Tulare and Kern Counties.

He was arrested by US border police in western Arizona in 2013 after a records check showed that he was wanted on a homicide charge in Alabama’s Lawrence County. He told investigators he was a debt collector for a Mexican drug cartel.

After being sent to Alabama, Mr Martinez was charged with the execution-style killing of Jose Ruiz, a man who allegedly “disrespected” his daughter, said Tim McWhorter, captain of the investigation division at the Lawrence County Sheriff’s Office.

Prosecutors in California say the killings took place over 30 years.

PA/Reuters