The most popular attack on Che Guevara is that he was a cold-blooded murderer.

Let’s be honest. Yes, he killed people – he killed enemy soldiers when he was fighting in Cuba, in the Congo and in Bolivia. He killed deserters and traitors to the revolution. He killed murderers and rapists who committed their crimes against the Cuban peasants during the Revolutionary War. After the Revolution, he gave death penalty to all those people who committed crimes against civilians during the Batista regime.

Just one remark: at war soldiers kill soldiers – in every country. If a soldier kills an enemy soldier, he is considered a hero. Why is it only Che Guevara who has been called a bloody murderer while he did just the same thing that every soldier does?

Che believed in the necessity of violent fight during the revolutionary struggle (after witnessing how the US-backed force brutally overthrew the democratically elected government in Guatemala) – but he never killed people for fun. He shot enemy soldiers during the fights but he also gave the injured ones first aid and medical help. When he knew that there were civilians around, he did his best to keep them away from the battlefield.

After the victory of the Revolution, Che became the commander of the fortress of La Cabaña and it was him who had to set up a tribunal at La Cabaña to judge all the people who committed crimes, tortured and killed during Batista's regime. He examined and reviewed the cases with the judges and he had the final word after the appeals had been heard. He could offer pardons or order execution. There were other tribunals in several Cuban cities and several hundred people were tried and executed – for example, at the other end of the island Raúl Castro was in charge of a similar procedure. Still, it is only Che who was named the "Butcher of La Cabaña" for this activity.

The name was given to him by the enemies of the Revolution, by such people who left Cuba after the Revolution because they disagreed with Fidel Castro's political ideas or because they were US employees and lost their jobs.

These people said that Che killed thousands of people – while actually there is no proof for this. According to less partial sources, about two hundred or less people were condemned to death during the trials.
Che has been also accused of being a sadist who went around cracking skulls and organising mock executions. Of course, there is no reliable proof for this either – only the words of bitter Cuban exiles. (However, Che did have mock executions during the revolutionary war in order to teach a hard lesson to his soldiers and to warn them against desertation – that was punished by death at war times.)
They also say that Che executed teenagers. Even if it were true, we must not forget that during the revolutionary war, on both sides, many of the soldiers were really young. Even fifteen-year-old boys joined the guerrillas and Batista’s army recruited such young men.

Che did say: "It is not possible to tolerate even the suspicion of treason." and "We do not need to use bourgeois legal methods - the proof is secondary." Remembering the lesson he had learnt in Guatemala, he didn't want to give the enemy the opportunity to regroup and organise a resistance.
What is always forgotten by the enemy voices is that the general public in Cuba supported him: they immediately wanted to punish Batista's men who oppressed, tortured and killed so many people during his regime. There was a fear of a massacre coming so the revolutionary government decided to solve the problem in their own way.
Che chose only judges with high reputation because he wanted morality to triumph over vengeance. The prisoners received lawyers and witnesses were heard in public. Che rarely attended these events - he spent the evenings discussing the cases and the evidence with the judges before making a decision. He thought that the enemy must be executed in order to defend the young revolution.

The Mexican historian Paco Ignacio Taibo II, who published a detailed biography about Che, wrote in this book:

"Fidel launched a counterattack to the U.S. campaign in a speech he gave January 21 at the National Palace, comparing the crimes committed during the dictatorship with those judged at Nuremberg and asserting the people's right to see justice done and to carry out the executions. He asked for a show of hands: was justice meted out to the torturers? According to Carlos Franqui, who was editor of Revolución at the time: "Fidel's question was answered by an overwhelming 'Yes!' A private nationwide survey showed 93 percent in favor of the trials and shootings." Che was present at the gathering, but took no part in the demonstration." […] "Without a doubt Che was in favor of the summary trials, but the tales woven by Cuban exiles, in which he was the "Butcher of La Cabaña," presiding over most of the shootings in Havana, are flights of fantasy. Revolutionary Tribunals No. 1 and No. 2 did sit at La Cabaña, the first trying policemen and soldiers, the second (which did not pass death sentences) trying civilians. RT1, presided over by Miguel Ángel Duque de Estrada, did pass the death sentence in some cases, at least two dozen of which were in January. Che did not sit on either tribunal, but did review appeals in his capacity as commander. He could have had no doubts as he ratified the sentences; he believed in the justice of what he was doing and over the previous years had become very tough-minded about such situations."