The document, complete with a forged stamp of the CNI logo, uses technical language to describe the operation meant to culminate in the sale of seven of the victim's organs.
The whole operation was to proceed under the "protocol EP-241-W2 of the United Nations", with the victim tried in an "anti-terrorism court".
Police said in a statement that the officers arrested the two women and then "set about tracing and detaining the male suspect".
The supposed victim of the murder plot was later found "in perfect health", the statement added.
The women, aged 52 and 20, according to the EFE news agency, could be charged with intention to commit murder, while the 29-year-old fake spy is likely to be accused of various kinds of fraud.
In a raid on the male suspect's home, police found a CV in which he claimed to be a crack marksman who could speak 22 languages, including Latin and Hawaiian. The man, who said he worked for Mossad and the CIA, claimed on a false service record to have taken out 1897 "objectives", while capturing another 524 in a total of 352 completed missions in 104 countries. He listed a total of 46 medals won during these missions.