The common law wife of jailed Mexican drug kingpin Joaquin "El Chapo" Guzman is stepping up her crusade to secure better treatment for her husband as he awaits possible extradition to the U.S. on an array of federal drug charges.

Emma Coronel Aispura was recently in Washington to meet with members of the Inter-American Commission on Human Rights, an independent offshoot of the Organization of American States (OAS).

'El Chapo's Family Wants International Investigation

Insisting that her husband is suffering from the "worst torture that exists," including sleep deprivation, Aispura is now calling for an international investigation into his harsh treatment, part of which she speculates is in retaliation for his high-profile 2015 prison escape that left Mexican President Enrique Pena Nieto red-faced with embarrassment.

During her time in the U.S., an attorney for Guzman claims Aispura was routinely followed by what she assumes were U.S. government agents.

Reputed as one of the world's most notorious criminals, Guzman was recaptured in Mexico earlier this year and soon after that Aispura accused prison authorities of "killing him slowly."

In one instance, she alleges guards awoke him every two hours at night to take roll call, and held loud conversations outside his cell as a guard dog followed his every move.

Just last month, Guzmán was transferred from a top security prison near Mexico City to a jail in Ciudad Juárez, located near the Texas border. The transfer came soon after the Mexican government granted two U.S. extradition requests.

Guard Found Murdered

Meanwhile, Mexican authorities are continuing their probe of the recent killing of a guard assigned to guard the outside the prison where the man once hailed as the "the biggest drug lord of all time" is being held.

Jorge Maurico Melendez Herrera, 20, is reported to have died of a blow to the back of the neck. He had also been stabbed numerous times. As many as 300 soldiers have now been assigned to provide security around the prison.

More recently, the remains of the seven men were discovered in Mexico's western Sinaloa state, otherwise known as the now jailed Guzman's old home turf. Authorities have not publicly indicated if they believe any of those killings are connected to Guzman or the Sinaloa drug cartel he once served as the face of.