El Chapo lieutenant Felipe 'The Engineer' Cabrera Sarabia asks Chicago judge for mercy

CHICAGO (WLS) -- Felipe Cabrera Sarabia, known as "The Engineer," is a drug trafficker considered to be one of Joaquin "El Chapo" Guzman's most trusted lieutenants. He was the drug lord's Chief Engineering Officer, known for his ability to design drug routes and the disappearance of naughty cartel operatives, according to authorities.

Prosecutors in Chicago are aiming to lock up Cabrera but the 53-year-old claims he's just a cattle herder who lost his way.

READ MORE: Accused Sinaloa cartel top operative Felipe Cabrera Sarabia trying to avoid more jail time

According to U.S. drug agent, Cabrera stepped up his cartel performance to meet El Chapo's demands. Mexican authorities said he has also been involved in the mass disappearances of the cartel's rivals, later found in sprawling graves.

Even though El Chapo is locked up for life and Cabrera has been out of circulation for more than a decade, Cabrera will face a possible sentence of 20 years or more when a Chicago judge determines his fate later this month.

Cabrera's case, and his one-time position as Chapo's CEO, is considered so sensitive years after the fact that a court document filed Wednesday by government attorneys has sizable sections blacked out to protect the identity and safety of witnesses and informants.

Cabrera is thought to be so dangerous that federal prosecutors are asking he be locked up for decades despite his guilty plea.

On the other side, Cabrera himself paints a far less menacing self-portrait.

He describes a childhood where he "left elementary school to help his father herd cattle." And by 12 years old, was independently managing his own herd and by 18, he was buying and selling cattle himself."

But it wasn't a herd of cows that landed Cabrera in federal lockup; it was kilos of cocaine and heroin flooding metro Chicago streets.

Cabrera is asking for a prison sentence of less than half of what the government wants.

When federal charges were first filed, the drug trafficker's venerable Chicago attorney Ralph Meczyk told the I-Team that they were "false accusations" made by "hardened criminals."

Thursday Meczyk declined to comment with sentencing on the horizon, but on July 25 the defense tone may be slightly softer as Cabrera is expected to say that "drugs ruin communities." He will plead for mercy and the chance, as he puts it, "to re-enter society."