Heir to an Execution: a film by Ivy Meeropol

My grandparents were Ethel and Julius Rosenberg, who were American-Jewish members of the Communist Party, executed by electric chair in 1953 for conspiring to pass atomic secrets to the Russians during the Second World War. In my mind, the government murdered my grandparents – it is now clear that my grandmother was not involved and my grandfather's guilt has never been wholly proven. Whatever he did, he didn't deserve to die like that.

When I was very young, I didn't want to know about what happened to my grandparents. I think I was scared of making the connection between them and the electric chair – my grandmother had an appalling death, a ghastly plume of smoke rose from her head as she was given electricity three times. She was in the chair for five minutes before she died.

She was used by the government, charged on the evidence of a false testimony given by her brother, David Greenglass. They used her to try to break her husband Julius. By threatening to execute her, they hoped that he would confess. When he refused, with her blessing, they executed her. I am outraged by the way she was treated.

Killing her wasn't even enough. They wanted to ensure that she went down as a woman who didn't care about her children and believed communism was more important than being a mother. None of this was true: she adored her children. Ultimately, she did what she believed to be best for them. My father was 10 at the time. He remembers his last visit with his parents the day before they were executed. He couldn't understand why they seemed so calm. He yelled at them: "There's only one more day to live!" This broke my grandmother's heart. She wrote him a last letter explaining how distraught she was, but how she was trying to remain calm so as not to upset him. It must be one of the saddest letters ever written.

On the day of the execution, my father and his brother Robert were sent into the garden to play baseball. He knew it had happened when he felt the shift of emotions among the adults: some started to cry. One woman turned to him and said: "I guess you'll be staying here with us." "I guess I will," said my father. He didn't cry.

No one from the family took my father or his brother in: everyone was either ashamed or too scared. They didn't want to be associated with Communists at that time, for fear of being terrorised by the government. My father is not bitter about any of this. "They would have lost their businesses if they had taken us in," he said.

Fortunately, my father and my uncle were adopted by Abel and Anne Meeropol, who were leftist intellectuals, a wonderful couple. Abel wrote the song "Strange Fruit", famously sung by Billie Holiday. Some people would have brought my father up telling him what terrible choices his parents made. The Meeropols didn't. They kept the Rosenberg spirit alive.

Growing up, I was in awe of my grandparents. They never felt like real people, they were martyrs, idols in their own home. They were exalted by the left and vilified by the right. I was treated differently in my home town of Wilbraham, Massachusetts. It was the same at college. I kept quiet about my background but people always found out who I was, some left-leaning professor would recognise my name. I felt something like a celebrity.

For years, I resisted the urge to make a film about my grandparents, but in my mid-thirties, I decided to do it. I was angry about what happened, but I also wanted to bring my grandparents down to earth and get a sense of who they really were, as human beings. I wanted to understand them. I wondered how they became so strong that they could go all the way to their deaths for something they believed in. If they had named their friends and comrades, they could have got off, but they refused to indict others. They also refused to betray each other, and my grandmother refused to manipulate Julius into confessing. There was an intense connection between them. As Abe Osheroff said, they were comrades in the deepest sense of the word.

If my grandmother had been let off, which could have happened had she complied with the government, she would have had nowhere to go and she would have been without Julius. She and her children would have been ostracised. She had an awful relationship with her own family. Her mother was very hard on her, and ridiculed her love of the arts. When Ethel first met Julius, she clung to him. He adored her and thought her artistic side was brilliant – she was an opera singer. In a way, she had no choice but to go to the chair with him.

I didn't enjoy making the film. It was very painful and I wondered why I was putting myself through it. I called cousins and relatives to whom my father had not spoken since his parents were executed, and they refused to talk to me. The fear and shame from 50 years before was still there. I tried to contact my grandmother's brother, David Greenglass, who is still alive. He lives not so far from me. He was the one who made up a false testimony against her. He told the court that she had typed up notes containing US nuclear secrets that were later turned over to the KGB. In 2001, he came out in public and admitted his lies. He said that he gave false testimony to protect himself and his wife Ruth, and that he was encouraged by the prosecution to do so. He actually admitted: "I would not sacrifice my wife and my children for my sister."

In my family, Greenglass has always been the embodiment of evil. He refused my request for an interview and told my cousin that she should not talk to me any more as the Meeropols are not to be trusted. I drove past his house during the film. It was part of my letting go. I realised that he wasn't evil, just a sad, pathetic character. I don't want to hold on to the bitterness. I'm still angry, and always will be, but there is no point in remaining bitter.

I intended the film to be a healing process for everyone. My father has an amazing attitude towards what happened: "Yes, it was horrible. But look at all the horrible things America has done all over the world."

'Heir to an Execution', a film by Ivy Meeropol, will be screened at the ICA, London SW1 (020-7930 3647), at 4pm on 11 November, as part of the Jewish Film Festival.

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