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, reports the BBC.
A group of gunmen burst into the president's private residence in the early hours of Wednesday. Mr Moïse's wife, Martine, was injured in the attack 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 control 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. Ariel Henry had been named this week as the new PM but he has not yet been sworn in. He insists he should be in charge.
Mr Joseph, the interim prime minister, told the BBC he was "puzzled" by Mr Henry's statement, adding: "We need to leave those things behind and put Haiti forward."
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.
How did the attack unfold?
Heavily armed assassins stormed the president's home in the hills above Port-au-Prince at around 01:00 local time (05:00 GMT) on Wednesday.
Video released after the shooting appeared to show heavily armed men dressed in black pretending to be US drugs agents, shouting: "DEA [US Drug Enforcement Administration] operations, everybody stay down!"
Mr Moïse died at the scene. The president's body had 12 bullet wounds, Magistrate Carl Henry Destin told Le Nouvelliste newspaper.
The president's office and bedroom were ransacked and he was found lying on his back, covered in blood, the magistrate said.
The first couple's three children, Jomarlie, Jovenel Jr and Joverlein, are reportedly in a "safe location", officials said.
Even before President Moïse's assassination, the situation in Haiti was marked by instability and there had been widespread protests demanding his resignation.
Parliamentary elections should have been held in October 2019 but disputes delayed them, meaning Mr Moïse had been ruling by decree.