Security forces in the South American overseas territory of French Guiana have arrested a man suspected of having killed a member of the gendarme police force, according to the local prosecutor's office.
The 20-year-old man was arrested by members of the same unit, the GIGN, and taken into custody on Saturday in connection with last month's shooting, Yves Le Clair, the prosecutor for Cayenne, the capital of the overseas territory, told the AFP news agency.
The suspect, a Brazilian, was arrested after having indicated that he was ready to surrender, Le Clair added.
He is under provisional arrest since Sunday and will be transferred to the French Carribbean island of Martinique.
The slain police officer, 35-year-old Arnaud Blanc, was part of a joint operation with the French army against illegal gold mining when he was shot dead on 25 March.
Investigators' preliminary findings suggest the suspect is a member of a gang involved in illegal gold mining.
French authorities fear the illegal gold extraction is a major source of pollution affecting sensitive water systems.
Lucrative, dangerous and damaging
Last year, French authorities carried out more than 1,000 patrols in the Guiana forest against illegal gold mining operations, seizing 59 kilograms of mercury and five kilograms of gold, according to a report from local authorities.
Local mining operators say 10 tonnes of gold are illegally extracted from French Guiana each year by unauthorised gold miners known locally as "garimpeiros". The business is lucrative, but dangerous and very damaging to the environment.
Mercury is used to coagulate the tiny grains of gold washed out of the soil. A powerful neurotoxin, the waste mercury contaminates plants, fish and ground water, making its way into the human food chain.
The miners also indiscriminately destroy forest cover, exposing the soil to rapid erosion.
French Guiana is one of several overseas territories which remain part of France and which continue to be administered from Paris.