A former Olympic snowboarder from Canada who is wanted by American authorities for allegedly running a multinational drug trafficking network is facing additional charges in connection with the killing of a federal witness, US Attorney-General Pam Bondi says.

Ten other defendants have been arrested on charges in the federal indictment unsealed in California that accuses Ryan Wedding of orchestrating the January killing of a witness in Colombia to try and avoid extradition to the US.

Possible cartel connection

Authorities are offering up to $US15 million ($23 million) for information leading to the arrest of Mr Wedding, who is on the FBI's 10 Most Wanted Fugitives list.

He is believed to be living in Mexico under the protection of the Sinaloa cartel, with whom authorities say he is work

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