NEW YORK - An American drug enforcement agent says he purposely kept Mexican police in the dark about efforts in 2014 to hunt down the drug lord known as El Chapo.

A U.S. agent testified Wednesday that Mexican police were purposely kept in the dark about secret efforts in 2014 to hunt down notorious drug lord Joaquin "El Chapo" Guzman because they couldn't be trusted.

Drug Enforcement Administration Agent Victor Vazquez told a jury in Guzman's trial that he was the American liaison for an operation to try to capture the top leadership of the Sinaloa cartel. He demanded only Mexican marines on his team because he believed, unlike the police, they wouldn't tip off the cartel.

Involving police "was not going to work" because of the "corruption level," Vazquez testified in federal court in Brooklyn.

Deep-rooted corruption and ineffectiveness among police forces has led Mexico to rely heavily for years on the military -- and particularly the marines -- to combat drug cartels in parts of the country.

Using DEA intelligence about the whereabouts of the cartel bosses, a strike force of about 100 marines in helicopters and trucks first tried to capture Ismael "El Mayo" Zambada, but failed to find him in a raid at a ranch in Sinaloa, he said.

The trial day ended before Vazquez could describe efforts to find Guzman. The notorious kingpin was caught in 2014 but ended up escaping through a tunnel that was dug into his prison cell.

Guzman was recaptured in 2016 and sent to the U.S. to face drug-trafficking charges carrying a maximum sentence of life in prison. He says he's being framed by shady co-operators.

Earlier Wednesday, co-operator Alex Cifuentes acknowledged on cross-examination that he had told investigators that his Colombian cartel once paid for protection with a "monthly allowance" to "General Naranjo" -- an apparent reference to Gen. Oscar Naranjo Trujillo. The former general, who was known in his country for fighting drug-traffickers, denied the allegation on social media.