Portuguese police detain 20 in Operation Tranca Segura, dismantling prison drug network led by inmate

Operation Tranca Segura

Portugal's Polícia Judiciária detained 20 people on 10 and 11 August 2026 in an operation code-named "Tranca Segura," targeting a network that supplied drugs to prisons in Guarda, Viseu, Coimbra and Lamego. The suspects, 17 men and three women, face charges of aggravated drug trafficking, criminal association, money laundering and prohibited weapon possession. All detainees have prior criminal records for drug trafficking. The operation was carried out by the Department of Criminal Investigation (DIC) of the PJ in Guarda, with support from the prison guard corps, including its intervention and security group and three canine teams.

The investigation began in April 2025, when the Guarda prison detected drugs entering the facility and requested PJ collaboration. Luís Couto, director of the Guarda prison, said the partnership with the PJ was close and long-standing.

“This operation begins with a request for collaboration with the PJ in April of last year. The entry of drugs into the prison establishment was detected. It was possible to collect some evidence, which we sent to the Judicial Police of Guarda. From there, an investigation process was opened.”

Leadership from inside prison

Alexandre Branco, director of the PJ in Guarda, told a press conference on 13 August that the network was led by an inmate at the Guarda prison who had previously served a sentence for drug trafficking in Peru. The inmate sent a large part of the money from prison drug sales back to Peru. Branco described the investigation as extremely sensitive and difficult because the orders originated from within the prison walls.

“The command was inside the Guarda prison establishment. The mastermind is an inmate who served a sentence for drug trafficking in Peru, where he sent a large part of the money from sales inside the prisons.”

The suspects were experienced in drug trafficking and knew how police operate, taking protective measures to avoid detection. They introduced small quantities of drugs into the prisons so that, if intercepted, they would not face trafficking charges. Branco noted that while the quantity of drugs seized was not large, the amount of money seized was significant for the operation's scale.

Smuggling methods and seizures

Drugs entered the prisons through several methods. Three men and one woman were initially detained trying to introduce hashish pollen carried inside the body, cocaine concealed inside a meat roll, and synthetic drugs impregnated in supposed children's messages written on paper. The network used visitors who were not part of the criminal scheme to carry the drugs past prison gates, after external couriers delivered the narcotics to the prison doors.

Cocaine doses120

Heroin doses80

Ammunition rounds71

Mobile phones31

Drug-impregnated papers7

Precision scales4

Vehicles3

Firearms2

Cocaine doses

120

Heroin doses

80

Ammunition rounds

71

Mobile phones

31

Drug-impregnated papers

7

Precision scales

4

Vehicles

3

Firearms

2

Data from the article text

Authorities executed 23 search warrants (both residential and non-residential) and served 19 detention warrants. One additional person was detained in flagrante delito for possession of a prohibited weapon. Searches were conducted at the prisons in Guarda, Coimbra and Lamego. The group also distributed illicit drugs in the communities where members lived, particularly in the cities of Guarda and Viseu.

Investigation and next steps

The PJ conducted four prior detentions in flagrante delito during the investigation, and missed two others. Those two missed detentions allowed investigators to confirm that an organized structure was behind the drug entries. Alexandre Branco said the investigation's timeline allowed for a partial historical reconstruction of the network's activities.

The detainees will be presented to the Department of Investigation and Penal Action (DIAP) in Guarda. The investigation lasted approximately a year and a half, according to Luís Couto, who described the results as positive despite the unfortunate circumstances requiring the operation.