A group of 28 foreign hitmen, including retired Colombian soldiers, assassinated Haiti’s President Jovenel Moïse earlier this week, police said.
After a gun battle in the capital Port-au-Prince, 17 people 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.
It is still unclear who organised the attack and with what motive.
The attack took place in the early hours of Wednesday, when gunmen broke into the president’s home 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.
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 home, 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 confirmed that at least six of the suspects appeared to be retired members of its military. It has pledged to assist Haiti with its investigation efforts.