Security forces inspect the site after an attack at the residence of Haiti's president Jovenel Moise in Port-au-Prince, Haiti on Wednesday. Photo: VCG

The widow of Haiti's slain president Jovenel Moise returned home Saturday after being treated in Florida for wounds she suffered in the attack, an official said.

Martine Moise, 47, with her right arm in a sling and wearing a bulletproof vest, was received at Port-au-Prince airport by interim prime minister Claude Joseph, secretary of state for communications Frantz Exantus wrote on Twitter.

Under gray skies and buffeted by strong winds, the first lady gingerly descended the steps of the plane, before firmly shaking hands with those assembled to welcome her, as seen on a video posted on social media.

"The first lady... has just arrived in Haiti to take part in preparations for the state funeral" of her late husband, Exantus wrote, posting pictures of Martine Moise disembarking from a private plane accompanied by multiple security agents.

She had spent 10 days in hospital in Miami, Florida, where she had been airlifted after her husband was gunned down in their home in the early hours of July 7.

The state funeral services are set to take place on Friday in Cap-Haitien, a historic city in the north of Haiti, which has slid dangerously toward chaos since Moise was killed. The day before Moise's widow's return, Joseph had pledged justice would be served for the president's assassination.

Police chief Leon Charles told a press conference Friday that Haitian authorities were "working with international agencies specialized in judicial investigations, such as the FBI [US Federal Bureau of Investigations], Interpol and other bodies that are on the ground to analyze all the evidence... to trace the masterminds of the assassination."

Moise, 53, was assassinated by a hit squad made up mostly of Colombian mercenaries, but many of the details surrounding the brazen attack remain a mystery. 

Colombia's police chief Jorge Vargas has said that a former Haitian justice ministry official, Joseph Felix Badio, gave two of the Colombian mercenaries the order to kill the president. But it is not clear if Badio in turn was following orders from someone else.