The Sinaloa cartel wanted to smuggle 100 tons of cocaine on an oil tanker - one of many shocking revelations from the son of one of the cartel\'s top leaders

• The trial of Sinaloa cartel chief Joaquin "El Chapo" Guzman entered its third month in January.
• Numerous witnesses described his role as leader of one of the most powerful criminal groups in the world.
• The son of one of Guzman's closest partners recently took the stand.

A dizzying amount of detail about the operations one of the most powerful criminal organizations in the world has been spilled by witnesses in the trial of Sinaloa cartel chief Joaquin "El Chapo" Guzman, which began in November.

The first days of January saw one of the case's most high-profile witnesses, Vicente Zambada Niebla, son of Ismael "El Mayo" Zambada, who is considered to be Guzman's peer within the cartel hierarchy and who Guzman's defense has tried to cast as the cartel's true leader.

The 43-year-old Zambada and Guzman, who is about 60 years old, reportedly exchanged nods and smiles when they first saw each other in the courtroom.

Since then, the younger Zambada, nicknamed Vicentillo, has described in extensive detail the exploits of the cartel that he was involved in from an early age.

Zambada pleaded guilty to drug-trafficking charges in Chicago in 2013, the first sign he could turn against his erstwhile cartel. He pleaded guilty to another trafficking-conspiracy charge in Chicago days before Guzman's trial began in New York City.

Zambada said on January 3, his first day on the stand, that he was testifying against Guzman in hopes of getting a reduced sentence and that his family had already been brought to the US.

Zambada's contact with the DEA has led to accusations of US allowed the Sinaloa cartel to operate in exchange for information on its rivals - while facing trial in Chicago, Zambada's lawyers claimed he was spying for the DEA for this very purpose. Prosecutors denied such an arrangement existed, and the judge in the case did not allow Zambada to argue it did. (The judge in Guzman's case has also prohibited the argument.)

US officials have said contact with such figures is a standard part of investigations. Vicente testified that both his father and Guzman passed information about their rivals to the US.

Mike Vigil, former chief of international operations for the DEA, said details from just one of the witnesses presented so far would probably have been enough to convict Guzman.

"There's so many people saying the same thing in terms of drug smuggling, association with Chapo Guzman, tape recordings, ledgers," Vigil said, that it would be enough to sink Guzman's defense.

While many had presented accurate details, Vigil disputed parts of their accounts, specifically allegations that US authorities agreed to overlook what cartel figures were doing in exchange for information, and cast doubt on allegations that former Mexican presidents had taken bribes, as previous witnesses have alleged.

Those payments would have been unlikely in light of efforts by previous Mexican leaders to crack down on criminal groups, and had they existed, Vigil added, those leaders would have been less likely to extradite cartel members to the US where they could reveal details.

Guzman's defense has argued that Zambada's father, El Mayo, is in fact the cartel leader.

According to New York Times reporter Alan Feuer, Zambada testified that Guzman "knew I was going to come testify against him." Even though his testimony implicated Guzman, "My compadre Chapo is not the enemy," Zambada told the court.

In the months after Guzman's arrest in January 2016, violence spiked in some parts of Mexico, as fight for control of the cartel played out between Guzman's sons, allied with "El Mayo" Zambada, and other rivals. Testimony of Zambada's son and brother in Guzman's trial doesn't appear to have strained that relationship, Vigil said.

"I don't think there's any tension right now. It may cause a little bit of problems for Mayo, but Mayo's leadership is solid as concrete within the cartel," but there may be "consternation" within the cartel, Vigil said.

"There has to be," in light Zambada's son and brother testifying, he added. "Chapo loyalists within the cartel may blame Mayo for that, but right now there's no signs of cracks."