A hit squad composed mostly of retired Colombian soldiers assassinated Haiti's President Jovenel Moïse earlier this week, police say.
The group included 26 Colombians and two Americans of Haitian origin, police chief Léon Charles told reporters.
Eight of the suspects are still on the run, while 17, including the two Americans, have been arrested.
The remaining suspects were shot dead during gun battles with the police in the capital, Port-au-Prince.
In the early hours of Wednesday, a group of gunmen broke into the president's home and shot him and his wife. Mr Moïse was found lying on his back with 12 bullet wounds and died at the scene, according to authorities.
His wife Martine was seriously injured and has been flown to Florida for treatment, where she is said to be in a stable condition.
It is not yet clear who planned the attack or what motivated it. Haiti's interim Prime Minister Claude Joseph, however, told the BBC that the 53-year-old president may have been targeted because he was fighting "oligarchs" in the country.
On Thursday, police presented some of the suspects to the media along with weapons, Colombian passports and other evidence. "Foreigners came to our country to kill the president," Mr Charles said.
"We will strengthen our investigation and search techniques to intercept the other eight mercenaries," he added.
Colombia's government has said at least six members of the alleged hit squad appeared to be retired members of its military. It has pledged to assist Haiti with its investigation efforts.
The US state department, meanwhile, said it could not confirm if any of its citizens had been detained.
Investigators are still searching for the masterminds of the killing, which has triggered some civil unrest in what is the poorest nation in the Americas.
An angry crowd gathered on Thursday to watch the police operation in the capital. Some cars were torched, and people gathered outside a police station where the suspects were being held.
A state of emergency remains in force across the country.
Who is in charge of the country?
The assassination has prompted confusion over who is in charge of Haiti. The constitution says the president of the Supreme Court should take over, but he recently died of Covid-19.
After that, amendments suggest the prime minister should lead. During his four years in office, Mr Moïse had six prime ministers and on Monday, a day before he was killed, he had nominated a seventh, Ariel Henry.
Mr Henry had not yet been sworn in, but insists he should be in charge.
Mr Joseph, the interim prime minister, told the BBC he was "puzzled" by Mr Henry's statement.
The UN has said Mr Joseph should remain in charge until elections are held later this year.
He has said he will not stand for the presidency. "I'm not here to stay too long. We need to hold elections. I do not have a personal agenda," he said.
SOURCE: BBC