MIAMI—A Haitian-Chilean businessman considered a key suspect in the killing of Haitian President Jovenel Moïse appeared in U.S. federal court on Thursday and was accused of providing weapons to former Colombian soldiers charged with fatally shooting the Caribbean country’s leader. Rodolphe Jaar, a former U.S. government informant who was recently detained in the Dominican Republic, was charged with conspiring to commit murder or kidnapping outside the United States and providing material support resulting in death, knowing or intending that such material support would be used to prepare for or carry out the conspiracy to kill or kidnap. Jaar, 49, is the second foreigner charged and arrested in the United States for his alleged role leading to the July 7 killing of Moïse at his private residence. In early January, former Colombian soldier Mario Antonio Palacios Palacios faced the same charges and remains detained at a federal prison in south Florida. …