Haiti sent security and investigation requests to Washington and the UN to secure its ports, airport and other strategic sites and to help with the probe after the assassination of President Jovenel Moise opened a power vacuum in the crisis-hit Caribbean nation, Haiti's Elections Minister Mathias Pierre told reporters on Friday.

"We thought that mercenaries could destroy some infrastructure to create chaos ... During a conversation with the U.S. secretary of state and the UN we made this request," the minister was quoted as saying. 

Reuters reported earlier that it had seen a copy of a letter from the prime minister's office to the UN office in Haiti.

The letter dated July 7 – the day Moise was shot dead in his home – said the appeal for assistance was "to support the efforts of the national police aiming to reestablish security and public order in the whole territory."

The U.S. State Department and Pentagon both confirmed receiving a request for "security and investigative assistance" and said officials remain in contact with Port-au-Prince.

White House spokeswoman Jen Psaki said on Friday that senior agents from the Federal Bureau of Investigation (FBI) and other officials would be heading to the Caribbean as soon as possible, but did not specify whether military troops would be deployed.

The UN did not immediately respond to a request for comment. A UN diplomatic source had earlier indicated that a Security Council resolution was needed to do as the Haitians had asked. 

Moise was shot dead in a pre-dawn attack Wednesday by a 28-member hit squad made up of 26 Colombians and two Americans of Haitian origin, Haiti's police chief Leon Charles said. The president's wife, Martine, was wounded.

According to the police chief, three members of the hit squad were killed by police and 17 taken into custody. Eight remain at large.

Haiti declared a "state of siege" hours after the president was assassinated, granting the executive additional powers.

Colombia's ex-soldiers involved

Colombia's police director on Friday said that 17 former Colombian soldiers are thought to have been involved in the assassination of Moise.

Two men who had died at the hands of Haitian police and 15 others under suspicion "may have belonged to the national army" of Colombia, having left it between 2018 and 2020, General Jorge Luis Vargas told a press conference.

The Colombian authorities did not specify the men's army careers or the reason for their departure from service. 

Colombia's El Tiempo newspaper said among those arrested was Manuel Antonio Grosso Guarin, 40, one of the country's most experienced soldiers.

Haitian police identified the two who died in crossfire with police are Haitian Americans - James Solages, 35, and Joseph Vincent, 55.

Investigation underway

Colombia also said on Friday it will send law enforcement and intelligence officials to assist Haiti after a number of its nationals were arrested in connection with the assassination.

A judge investigating the case told reporters that Moise was found lying on his back on the floor of his bedroom, with 12 bullet wounds and his left eye pushed in. The front door of the residence was covered in bullet holes and had been forced open, while other rooms were ransacked.

"His body was riddled with bullets," Petionville tribunal judge Carl Henry Destin said. "There was a lot of blood around the corpse and on the staircase."

The United States on Thursday pledged to send senior officials from the FBI and Department of Homeland Security (DHS) to Haiti as soon as possible to assess the situation and see how best they can assist, the White House said.

Two U.S. law enforcement sources, speaking on condition of anonymity to discuss an active investigation, said that agencies were looking into U.S. connections to the killing.

A State Department spokesperson said, "We are aware of the arrest of two U.S. citizens in Haiti and are monitoring the situation closely. Due to privacy considerations, we have no further comment."

The head of Colombia's national intelligence directorate and the intelligence director for the national police will also travel to Haiti with Interpol to help with investigations, Colombian President Ivan Duque said on Friday.

"We offer all possible help to find out the truth about the material and intellectual perpetrators of the assassination," Duque wrote on Twitter, saying he had just spoken on the phone with Haiti's interim Prime Minister Claude Joseph.

Haitian officials have not given a motive for Moise's killing or explained how the assassins got past his security details.

(With input from Reuters, AFP)