BOGOTA, July 15 (Reuters) - Many of the Colombian ex-soldiers accused of involvement in the assassination of Haiti"s president went to the country as bodyguards, Colombian President Ivan Duque said on Thursday, but others had detailed knowledge about the planned assassination. Haitian authorities have said President Jovenel Moise was shot dead at his home by a unit of assassins. Eighteen Colombians have been detained and three others killed by police. Families and colleagues back in Colombia have told journalists the men were hired to act as bodyguards. "There was a big group that were taken on a supposed protection mission, but within that group, there"s a smaller group, which were those who apparently had detailed knowledge of what was to be a criminal operation," Duque told local La FM radio.