Joaquín "El Chapo" Guzmán, leader of the Mexican Sinaloa drug cartel, may have been killed in a shootout.
Police are investigating reports of a man's body, resembling Guzman, being carried out in a car after a violent gang clash in Guatemala.
The armed groups, presumably fighting over territory, have battled it out in the San Martin village in Peten province, San Francisco municipality, near the Mexican border.
"We cannot say it is him, but it could be," Guatemalan Interior Minister, Mauricio Lopez Bonilla is quoted by Borderland Beat as saying.
The Mexican military has been sent out to search for the body in the jungle area. However, it has vanished, along with any sign of the shooting.
The Guatemalan government has reported on Thursday night that "there is no indication in Petén clash between drug traffickers."
A few hours earlier, they had confirmed the incident, allegedly deploying agents and forensic investigators to verify whether El Chapo was killed.
In a 2012 report, Gawker listed El Chapo as the most wanted man in Mexico. He has also been proclaimed Chicago's Public Enemy No. 1, this month.
The U.S. Treasury department, quoted by the Daily Mail, named him "the world's most powerful drug trafficker."
El Chapo, Spanish for "Shorty," as he is only 5ft 2in (157 cm) tall, was the most wanted man in the world in 2011, already escaping prison in 2001.
He has been captured in Guatemala on June 9, 1993 and imprisoned in Puente Grande, Jalisco in Mexico. He broke out on January 19, 2001 in a laundry truck, aided by insiders.
It's been 12 years since the drug lord who is allegedly worth $1 billion (€758 million) has had a $7 million (€5.3 million) bounty on his head.