The Costa Rican authorities have arrested the country's most wanted alleged drug trafficker, Alejandro Arias Monge, widely known as "El Diablo," in a major security operation that ended with one suspect dead and eight police officers injured.

The arrest was carried out on Friday in Rio Frio, Sarapiquí, following a coordinated operation targeting members of an alleged criminal network linked to drug trafficking and other violent crimes.

Arias, who had been on the run for nearly a decade, was wanted on multiple charges, including drug trafficking, murder, robbery, and money laundering. The United States Drug Enforcement Administration (DEA) had offered a $500,000 reward for information leading to his arrest.

According to Costa Rican authorities, the operation escalated into a fierce gun battle that lasted nearly an hour, during which approximately 2,500 rounds of ammunition were exchanged.

One suspected gang member was killed in the exchange, while eight police officers sustained injuries, including two who were reported to be in critical condition.

Security operatives also arrested two additional suspected members of the criminal organisation and recovered several high-powered firearms, handguns, and surveillance equipment from the scene.

Authorities believe Arias led one of Costa Rica's most violent criminal groups, allegedly linked to hundreds of killings and widespread drug trafficking operations across the country.

Describing the operation as a major breakthrough in the fight against organised crime, Costa Rican officials said the arrest marks a significant step in efforts to dismantle violent drug cartels and restore public safety.

The U.S. Embassy also welcomed the development, commending Costa Rican security agencies for the successful operation and reaffirming continued cooperation in combating transnational organised crime.