The suspect reportedly aimed a handgun and pulled the trigger at point-blank range toward Vice President Cristina Fernández, but it did not fire.
The Justice Department says Iran engaged in a murder-for-hire scheme targeting the former national security advisor.
Bipartisan blowback failed to stop the GOP senator from saying that "somebody in Russia" should "take this guy out by any means possible."
Police say Christian Emmanuel Sanon was in contact with a firm that recruited the suspects in the killing.
The Biden administration has so far given no indication of military help, though the FBI is aiding the investigation into President Jovenel Moïse's assassination.
Police killed four suspects and arrested two others hours later amid political instability in the Caribbean country.
Alexander Treisman, 19, looked up information on former Vice President Joe Biden's home address, state gun laws, rifle parts and more.
The president is campaigning as a peacemaker, and last week ran Facebook ads bragging about his nomination for the "Noble Peace Prize."
Jason Lee Van Dyke allegedly used the Proud Boys street gang to keep watch on a man he wanted to kill, according to authorities in newly released documents.
The man who killed RFK in 1968 is in stable condition in a local hospital.