The Cuban authorities have argued that those on board the pursuing vessels were dock workers acting on their own initiative and not government or law enforcement officials. However, several of the survivors have doubted this assertion and have alleged that the whole operation appeared to be coordinated and directed by radio from a coast guard vessel. The Cuban coast guard service falls under the jurisdiction of the Ministry of the Interior. Amnesty International believes that there is sufficient evidence to indicate that it was an official operation and that, if events occurred in the way described by several of the survivors, those who died as a result of the incident were victims of extrajudicial execution.
--"The sinking of the '13 de Marzo'", Amnesty International, July 1, 1997
The only evidence of an "official operation" in Amnesty's report is based interviews with two alleged survivors of the sinking of the 13 de Marzo. One was being held in the US Naval Base at Guantánamo Bay, Cuba. He was among thousands of Cubans in detention after being picked up by the US Coast Guard while trying to reach the USA by sea (after Cuban authorities ceased to intercept illegal departures). Choosing to remain anonymous, he said he had been picked up by one of the three pursuing tugboats after the 13 de Marzo sank. (This contradicts other accounts saying that the tugboats did not come to the aid of the survivors in the water. Some accounts even claim the tugboats created a "whirlpool" effect to drown them -- physically impossible, to my knowledge.) He also said that although those on board these three vessels were dressed in civilian clothes, he did not believe, as the Cuban authorities clamied, that they were ordinary dock-workers, especially as several of the crew of one boat appeared to be suffering from seasickness!
Their second witness, Sergio Perodin Pérez, interviewed two years later in the USA, said that a Cuban coastguard vessel, which had followed the 13 de Marzo and the other three tugboats out of the port, "appeared to be directing operations by radio." How he was able to make that determination is left to the reader's imagination. Amnesty's report does not say anything further about these alleged radio transmissions. Not even if they were actually overheard by Pérez or any of the other survivors. If they had such information, it most certainly would have been featured prominently in their report. And while it is likely that there was some radio contact, it is a stunning speculative leap on the part of Amnesty International to go from this to claiming that the crews of the pursuing tugs were being directed to sink the 13 de Marzo as part some kind of high-level conspiracy!
Pérez also said that he believes, from information that he and other survivors were able to obtain from "various sources," that the authorities had found out about the hijacking attempt some time beforehand and were lying in wait for them--presumably to make some kind of example of them. As Amnesty reported, however, all survivors were rescued by the crews of the pursing tugboats or the coast guard vessel in this case. In addition, the Cuban government, only a few days after this regrettable incident, ceased to intercept any illegal departures by sea, allowing large numbers Cubans to "escape" to the US. Now, what kind of "example" was that?
The US government put an end to this exodus itself with its infamous "wet-foot-dry-foot" policy. The US Coast Guard, since then, has tried, with mixed success, to intercept illegal, would-be immigrants from Cuba at sea (wet feet) and repatriating most of them -- as it would for other countries of the region. Those that manage to evade the Coast Guard in a deadly cat-and-mouse game, however, can claim their "prize" of automatic US residency status -- for Cubans only! Remember that even at the time of the sinking, tens of thousands of Cubans had been legally emigrating to the US every year.
So, Amnesty's case rests entirely on (1) the opinion of one survivor that members of the crew of one of pursing tugboats appeared to be seasick, and (2) on questionable evidence from another survivor interviewed in the US two years later about supposed radio transmissions from a Cuban coast guard vessel and hearsay from "various sources." That is Amnesty's "sufficient evidence" that this was some kind of official operation or government plot! These baseless accusations are proof of a clear, anti-Cuban bias in this case.