The United States is becoming increasingly involved in the investigation of Haitian President Jovenel Moise's murder, with key suspects facing the prospect of trial in U.S. courts as a probe by the Caribbean nation's authorities stalls.

Congress earlier this month ordered the U.S. State Department to produce a report about the July 7 assassination, which deepened a political power vacuum in the western hemisphere's poorest country and has emboldened the powerful gangs who serve as de facto authorities in parts of Haiti.

The judge who had been in charge of the case, Garry Orelien, said in a telephone interview he welcomed U.S. interest in the case as it would help him advance the stalled probe.