Press freedom groups in Mexico are pushing for a man in U.S. custody to face justice in Mexico for the murder of a high-profile journalist.

Famed Sinaloan reporter Javier Valdez was gunned down in 2017, and the man the Mexican government accuses of ordering the assassination — Damaso Lopez Serrano — has been in U.S. custody for more than five years on drug conspiracy charges. A U.S. federal judge recently cut his sentence short, raising fears among some press freedom groups that he could evade efforts to extradite him to Mexico to face justice in Valdez’s killing.

But Jan-Albert Hootsen, the Mexico representative for the Committee to Protect Journalists, said if he remains in U.S. custody for years more on other charges, that could also derail efforts to resolve the Valdez murder.

“It is of the utmost importance that this particular case, which was the most notorious one of the past few years, is actually solved,” he said.

But Hootsen acknowledged that getting Lopez Serrano back to Mexico won’t be easy.