Mongols bikie Wade Yates-Taui has warned his girlfriend during an appearance in a downtown Los Angeles court not to "talk to anyone".
The 22-year-old Queenslander, wanted for his alleged role in the stabbing death of rival bikie associate Max Waller on the Gold Coast on June 23 last year, was arrested on the weekend by US Marshals in the Californian mountain resort of Big Bear Lake.
Yates-Taui faces an unlawful killing charge in Queensland.
US District Court judge John McDermott was told during Wednesday's brief appearance, US prosecutors were waiting for Australian authorities to file formal extradition papers for Yates-Taui.
Australian authorities have 60 days to do so from the time of Yates-Taui's arrest.
He did not apply for bail and is being held in Los Angeles' Metropolitan Detention Center.
As he was being led out of court his model girlfriend, Raquel Petit, shouted: "I love you."
The cage fighter replied: "I love you too. Don't talk to anyone".
Court papers filed in the US District Court allege Yates-Taui was served with a subpoena in Queensland on December 5, 2013, to appear before the Queensland Crime and Misconduct Commission for a December 11 hearing on his alleged involvement in the fatal stabbing of Waller.
Yates-Taui did not show up and immigration checks revealed he left Australia for Indonesia on December 10, then went to Singapore before arriving in Los Angeles in March, 2014.
US Marshals, after being alerted by Australian authorities, monitored Yates-Taui and Petit, as they travelled around California, visiting Venice Beach and Big Bear Lake.
The surveillance included tracking the couples' Facebook online postings.