The Haitian police say a group of foreigners, including retired Colombian soldiers, assassinated President Jovenel Moise.
Leon Charles, director of Haiti’s national police, said at least 28 people, comprising 26 Colombians and two Haitian-Americans, participated in the murder.
Charles said 15 Colombians and two Haitian-American suspects have been arrested while eight are still on the run.
He added that two of the suspected assassins were killed during a gun duel with security forces.
“Foreigners came to our country to kill the president,” Charles said.
“We will strengthen our investigation and search techniques to intercept the other eight mercenaries.”
The suspects were paraded by the Haitian police on Thursday, along with ammunition allegedly seized from them.
Moise was assassinated after gunmen broke into his private residence in Pétion-Ville, Port-au-Prince, the capital, in the early hours of Wednesday.
According to authorities, Moise was found lying on his back with 12 bullet wounds and a gouged eye.
Martine Moise, the first lady, was also wounded in the attack.
The first lady has been flown to Florida for treatment where she is said to be in a stable condition.
The motive for the assassination is yet to be known.
The Colombian government had also said at least six of the suspects appeared to be retired members of its military.
Diego Molano, Colombia’s defence minister, pledged that the country will assist Haiti with the investigation.
The Taiwanese embassy in the country also confirmed that 11 of the suspects were arrested in its diplomatic compound after security operatives discovered that “a group of armed men had broken into the courtyard”.
The killing has triggered civil unrest in Haiti while a state of emergency remains in force across the country.