In the past few days, Americans have become aware that convicted Mexican drug lord Joaquín Guzmán Loera -- a man better known as"El Chapo" ("Shorty" in English) --has once again escaped from a Mexican prison.

This time, Guzmán wriggled out of state custody through a tunnel beneath a shower stall in a maximum-security Mexican prison. And this has understandably done damage to the reputation of Mexico's president, Enrique Peña Nieto, a young and conservative politician who ran on a platform of ending corruption and restoring law and order in drug-war ravaged Mexico.

Then, this week, the political fallout spilled across the border.

On Monday, Republican presidential candidate Donald Trump reportedly called the FBI asking for an inquiry into alleged threats that he received from Twitter accounts that might be operated by Guzmán's son or sons. And by Tuesday, fellow GOP presidential contender Marco Rubio used the Guzmán mess to reinforce his gripes with the Obama administration.

Guzmán, it seems, has become a U.S.  presidential campaign issue. So how did we get here?

Guzmán has an allegedly long and brutal criminal résumé studded with singular events for only some of which he has faced charges, trials or convictions. His Sinaloa cartel has reportedly supplied much of the cocaine and marijuana available in the United States for decades.

In the early 2000s, Guzmán escaped from another Mexican prison, that time aided by a  laundry cart and his diminutive size. During the 13 years on the run that followed, he evaded several near-captures with trickery, bribery and an action-movie-worthy arsenal of heavy and explosive weaponry.

Guzmán and his deputies also took on the mantle of being Robin Hood bandits, becoming frequent subjects of narcocorridos — a form of sung Mexican folktale or current-event-infused opera — sometimes commissioned by drug lords and their rivals.

But in 2014, Mexican law enforcement, with information provided by U.S. agencies, captured Guzmán.

Now for the campaign warfare on this side of the Rio Grande.

On Monday, the celebrity news Web site  TMZ and ABC News reported along with a number of Spanish-language publications that Trump had received expletive-laden, threatening messages from Twitter accounts possibly controlled by one or more of Guzmán's sons. The alleged threats -- one of which we found on Twitter but can only describe in family-friendly terms here because it's littered with Spanish-language expletives and homophobic slurs sometimes used in Latin America -- followed Trump's public statements about Guzmán since the reputed drug lord's Saturday escape.

Trump, to also put this in family-friendly terms, has said publicly that were he in the White House, he would kick Guzmán's posterior. And he's posted this on Twitter among other messages about Guzmán

But there's been no independent verification or named source confirming Trump's report to the FBI. The FBI generally will not confirm or deny the existence of investigations. After a round of referrals first to the law enforcement agency's national press office then its Washington and New York City field offices, The Fix was unable to confirm that Trump had, indeed, called the FBI on Monday or that any investigation into the tweets had begun.

By Tuesday morning, Rubio put out a statement blasting the Obama administration for what the statement described as the administration's failure to seek Guzmán's extradition to the United States in 2014.

(Rubio is the chair of the Senate Foreign Relations Committee's subcommittee on Western Hemisphere, Transnational Crime, Civilian Security, Democracy, Human Rights & Global Women's Issues. So this is an issue he has dealt with.)

In the United States, Rubio's statement implied, Guzmán might have been tried, convicted and held in a more secure facility. (U.S. officials reportedly pressed for extradition, but were denied by Mexico City.)

It's unclear that any U.S. prosecutors had sufficient evidence to bring criminal charges against Guzmán in the United States, but lets assume for a moment that they did.

Given that his drug empire has been implicated in not just trafficking substantial quantities of drugs into the United States but a number of violent crimes and brutal murders, it is possible that Guzmán could have faced charges in the United States in which a prosecutor would have wanted to seek the death penalty or a life sentence without the possibility of parole. And both might have been an impediment in bringing Guzmán to the U.S. for trail.

As early as 1861, the United States and Mexico have had an agreement in place that allows for the extradition of certain criminals between the two countries. But, since the 1980s, Mexico and several other countries have refused to send Mexican citizens to the United States to face changes for which they could face the death penalty. U.S. prosecutors seeking to extradite individuals wanted for murders in the United States have been forced to agree not to seek the death penalty in order to get the Mexican government to turn over wanted individuals.

And if that's not complicated enough: In 2001, the Mexican Supreme Court ruled that any charge for which a Mexican citizen could face life imprisonment without the possibility of parole constituted cruel and unusual punishment. The Mexican government has also begun refusing to send some fugitives wanted for alleged crimes in the United States back for trial without assurances that parole will be an option, the San Francisco Chronicle reported back in 2003.

And just to be extra clear here, Mexico is far from the only country that has set specific terms under which it will comply with American extradition requests. Since most countries no longer allow the death penalty, many will not send their citizens or even wanted fugitives from any other country to the United States for trial if the death penalty is a possibility.

And there's one other possible explanation for what became of that extradition request for Guzmán. It's a death penalty case in Texas.  In 2014, Texas earned the ire of the Mexican government and created an international incident when it executed, Edgar Tamayo Arias.

Tamayo was convicted in the 1994 murder of a Houston police officer. Mexico had protested his execution on the grounds that Tamayo was a Mexican citizen who after his arrest, was denied access to Mexican consular staff and the legal defense that staff would have made sure that Tamayo received. Both the Bush and Obama administrations encouraged Texas not to set an execution date for Tamayo but to instead set a court date where the international issues could be aired. Both administrations cited concerns about the fate of U.S. citizens in Mexican jails if Tamayo were executed. Texas refused and executed Tamayo in late January 2014.

One month later, Guzmán was captured in Mexico.

Regardless of the legal hurdles to extradition in the past, Rubio did indicate in his statement that the United States should offer any assistance possible to aid in Guzmán's recapture and arrest this time around, then request extradition as part of the deal.

So, at this moment, what we can say with certainty is limited to this:

Guzmán has become another matter for discussion on the campaign trail -- a talking point for both Trump and Rubio. Of course, the two candidates have mentioned Guzmán   in very different terms. But the precise facts around each of their  issues with Guzmán, the Mexican government and the Obama administration can't be closely scrutinized since so many of the details here are really quite unclear.