A Mexican attorney said Federal Police mistakenly arrested his client for allegedly belonging to the Los Zetas drug mob and having links to hit men who killed a U.S. immigration agent.

"My client is not ... the financier of the Los Zetas criminal organization. It's not true," defense attorney Rafael Heredia told Efe Wednesday.

He said 27-year-old Luis Miguel Rojo Ocejo was arrested on Feb. 26 along with his girlfriend at a restaurant in the central state of San Luis Potosi, 11 days after the killing of U.S. Immigration and Customs Enforcement agent Jaime Zapata in that same state.

The woman was subsequently released.

But the lawyer said that, according to his client, the time and place of his detention differ from what appears in the arrest report.

The report from Federal Police, from the people who supposedly arrested him, says they detained him on the street in San Luis Potosi (city) on Feb. 27. We're up against a big lie," Heredia said.

"To try to bolster their accusation, the police say they found two fragmentation grenades, one in his jacket and another in the car. That's completely false," he added.

Apparently, Rojo Ocejo's only link to Sergio Mora Cortes, another suspected Zeta member under arrest in the killing of the ICE agent, is that he met the latter once at a nightclub and gave him his telephone number.

Mora Cortes called Rojo Ocejo to ask where he could buy a luxury SUV and his cellphone number was recorded.

The lawyer says his client's situation is paradoxical because even though he has little money federal authorities accuse him of being the Zetas' financial operator.

He added that he hopes prosecutors understand that his client is not a criminal and do not put him before a criminal court judge, but that he is prepared to defend him "to the end" to see that "truth prevails."

Heredia is a well-respected defense attorney known for a case in which Antonio Zuñiga, whose story was told in the 2008 documentary "Presumed Guilty," was exonerated after spending 842 days in prison several years ago for a murder he did not commit.

The film exposed the corruption and lack of legal protection in Mexico's justice system.