Haitian police identified the two as James Solages, 35, and Joseph Vincent, 55, saying that they were part of a heavily armed commando unit comprised mostly of 26 Colombians, who sources in the Colombian army said entered Haiti from the neighboring Dominican Republic.
Two law enforcement sources, speaking on condition of anonymity to discuss an active investigation, said that agencies were looking into US connections to the killing, but declined to comment specifically on the two suspects.
The sources said US agencies were not assisting in the investigation in Haiti because Haitian officials had not requested their help.
A third source confirmed that US intelligence agencies were also looking into the matter.
Haitian authorities have said little to explain why Solages and Vincent, two Haitian-Americans from Florida, would have been motivated to join Colombian mercenaries to assassinate Haiti's president.
Solages described himself online as a "certified diplomatic agent" and the former "chief commander of body-guards" for the Canadian embassy in Haiti. Those statements were made on the website of a charity he ran, which was modified on Thursday to remove them. Reuters reviewed an archived version that remains accessible.
The Miami Herald quoted an unnamed government official as saying that a decade ago, when Solages was in his mid-20s, he briefly worked for a company that provided security for the Canadian embassy in Haiti.
"We are aware of allegations implicating an individual who was briefly employed as a reserve bodyguard by a security company hired by Global Affairs Canada in 2010," the newspaper quoted the official as saying.
Public records show Solages, a naturalized US citizen, lived in Tamarac, Florida, near Fort Lauderdale, and does not have a criminal record.
Florida records show Solages has held security officer and firearm licenses.
Solages also ran a business called FWA SA A JACMEL AVAN INC, which has described itself on its website as a charity focused on ending childhood hunger and improving education in Haiti.
Few details had emerged about Vincent by Friday.
Haiti's government has requested that the United States send troops to protect key infrastructure following the assassination of President Jovenel Moise this week, Elections Minister Mathias Pierre said on Friday, although The United States has no plans to provide military assistance to Haiti "at this time," a senior US administration official said on Friday.