A reputed onetime Sinaloa drug cartel lieutenant wanted someone to “split the head” of the godson of one of the world’s most notorious criminals, prosecutors say.

To make it happen, Jesus Raul Beltran Leon was ready to spend $25,000.

But a fellow prisoner caught him on tape. The beating never went down. And somewhere in the middle of it all was one of Chicago’s most notorious street gangs: the Four Corner Hustlers.

That much was revealed on the first day of Beltran Leon’s sentencing hearing at the Dirksen Federal Courthouse, where prosecutors are asking a judge to put away for 35 years a man they say worked with the sons of Joaquin “El Chapo” Guzman Loera to smuggle massive shipments of drugs into the United States.

They say he offered $25,000 for the severe beating of Guzman godson Damaso Lopez Serrano. Serrano testified against Beltran Leon on Monday, saying his father was at one point “the closest person to Chapo.”

Serrano testified that he understood that “gang members” had been enlisted to beat him at the jail.

He also testified about the Sinaloa cartel, saying Guzman “is my godfather” and admitting that he ordered between 13 and 15 killings. He accused Beltran Leon of shooting someone at a party and said Beltran Leon once bragged about being with Guzman’s son Ivan when Guzman called with instructions to pick him up after Guzman’s prison escape in 2001.

“Chapo told Ivan not to worry, that he was going to get lost for a while but that everything would be alright,” Serrano said. “And, after that, they just dropped him off somewhere.”

It was the plot against Serrano — and the nexus between the Sinaloa cartel and the Four Corner Hustlers — that hung over the hearing, which ended before prosecutors finished calling witnesses and will continue Tuesday.

Beltran Leon admitted in April his role in the sale of 46 kilograms of cocaine in Los Angeles between June 8 and June 10, 2013.

Prosecutors called attempted bank robber Andrew Johnston to the stand. He described conversations with Beltran Leon at the Metropolitan Correctional Center, the Dirksen Federal Courthouse and while the pair were being shipped between the two downtown Chicago buildings.

Johnston, who said he acted as a sort of jailhouse lawyer to other inmates, said Beltran Leon decided he wanted to plead guilty after he learned Serrano might testify against him. During one conversation, Johnston said Beltran Leon held up his hand and made a “finger-pull motion,” similar to someone pulling the trigger on a gun.

“I understood him to mean that he was telling me that (Serrano) could testify about violent acts,” Johnston said.

Serrano was being held on the same floor as Johnston. Johnston said he later heard $5,000 was being offered for Serrano’s beating. In a conversation he recorded with Beltran Leon, prosecutors say Beltran Leon said, “I heard 25,000.”

When Beltran Leon asked who had said $5,000 was being offered, Johnston said, “They’re two Four Corner Hustlers.”

The Four Corner Hustlers were tied in a federal racketeering indictment to six killings between 2000 and 2003, and prosecutors recently linked the gang to three more in 2012. Several members of the gang face trial next month. Three more — who could face the death penalty if convicted — are set to go on trial next year.