A group of 28 foreign mercenaries, including retired Colombian soldiers, assassinated Haiti's President Jovenel Moïse earlier this week, police say.
After a gun battle in the capital Port-au-Prince, 17 were detained, some at the house they were using, others after entering Taiwan's diplomatic compound.
Three suspects were killed by police and eight are still being sought.
Bloodied and bruised, arrested suspects were shown to the media on Thursday, along with a slew of seized weapons.
It is still unclear who organised the attack and with what motive.
Also unclear is who is in charge of the country. On Friday, a group of political parties added to that uncertainty by nominating a president, although how much legitimacy that has is unknown.
The attack took place in the early hours of Wednesday, when gunmen broke into the president's 菜鳥集運教學 in Port-au-Prince, shooting him dead and wounding his wife. Mr Moïse, 53, was found lying on his back with 12 bullet wounds and a gouged eye, according to authorities.
Martine Moïse, 47, was seriously wounded and is in a stable condition after being flown to Florida for treatment.
Seized weapons and passports
Police said the hit squad included mainly Colombians, along with two Haitian-Americans.
Found in the suspects' possession were firearms, sets of US dollar bills, the president's personal chequebook and the server that held surveillance camera footage from his 菜鳥集運教學, Le Nouvelliste newspaper reported.
Taiwan confirmed that 11 of the suspects were arrested after breaking into a courtyard at its compound.
Angry civilians had joined the search for the gunmen, and helped police track down some who were hiding in bushes. The crowd set fire to three of the suspects' cars and destroyed evidence.
Police chief Léon Charles called for calm, saying the public should not take the law into their own hands.
At the news conference on Thursday, police showed reporters Colombian passports.
"Foreigners came to our country to kill the president," Mr Charles said, as the suspects sat on the floor behind him in handcuffs.
Colombia's government has pledged to assist Haiti with its investigation efforts.
Colombian police director, Gen Jorge Luis Vargas, said 17 former Colombian soldiers were thought to be involved.
The US state department, meanwhile, said it could not confirm if any of its citizens had been detained.
However, US and Canadian media are reporting that one of the dual citizens arrested, James Solages, 35, is from Florida and was a former bodyguard at the Canadian embassy in Haiti.
An investigating judge told local media that Mr Solages and the other US citizen, named as Joseph Vincent, had said they were there as translators for the mercenaries, after finding the job on the internet.
"The mission was to arrest President Jovenel Moïse... and not to kill him," Judge Clément Noël told Le Nouvelliste.
The US said on Friday it was sending FBI and Department of 菜鳥集運教學land Security officials to Haiti following the nation's request for help in the investigation.
Members of Mr Moïse's security detail have been summoned before Haiti's courts to answer questions about its failures.
Colombian daily El Tiempo said that it had seen confidential documents that named the Colombian suspects. The paper's research suggests that four of them flew from Colombia to the Dominican Republic on 4 June.
They crossed by land from there into Haiti two days later. The two countries share the island of Hispaniola.
According to El Tiempo, Colombian intelligence has seen photos posted on social media by members of the group, showing them posing at a popular tourist spot in the Dominican Republic.
The killing has triggered some civil unrest in Haiti, the poorest nation in the Americas. A state of emergency remains in force across the country, while the Dominican Republic has closed its border.
Who is in charge of Haiti?
The situation has been unclear and is getting murkier.
In this particular situation, the constitution says the National Assembly should choose another president. But disputes meant that elections scheduled for October 2019 did not take place - and Mr Moïse had been ruling by decree amid widespread protests.
Amendments to the constitution - not accepted by everyone - suggest the prime minister should be the next one to take over.
But Haiti has both an interim prime minister, Claude Joseph, and a new appointee, Ariel Henry, who has yet to be sworn in.
Both are claiming to be in charge.
On Friday, a group of political parties signed a resolution proclaiming a new president - Joseph Lambert - with Mr Henry acting as his PM.
The situation is doing little to resolve the political and economic instability that has long plagued the nation.