What did Roy Cohn do? HBO documentary Bully, Coward, Victim explores his story

The doc will take an "unflinching look" at the reviled attorney and his role in executing Julius and Ethel Rosenberg.

The legal celebrity was known for assisting Joseph McCarthy's investigations into communism and later representing the likes of Donald Trump and Rupert Murdoch before being disbarred in 1986 – the year of his death.

Directed by Ivy Meeropol, the granddaughter of the Rosenbergs, this upcoming documentary examines Roy Cohn's dark legacy from a uniquely personal perspective.

Here's everything you need to know about who Roy Cohn was and what he's known for.

Who is Roy Cohn?

Roy Cohn, born in New York City in 1927, became a prominent attorney after being admitted to the bar and becoming involved in the Smith Act trials of Community Party leaders in 1949.

These trials saw 11 communist leaders sentenced to up to five years in prison for violating the Smith Act – a statute prohibiting the advocation of overthrowing the government. After the first trial, an additional 100 Community Party officers were prosecuted.

What did Roy Cohn do?

In 1951, Cohn played a large role in the espionage trial of Julius and Ethel Rosenberg – a couple accused of spying on behalf of the Soviet Union. Cohn prosecuted the pair, who were convicted of espionage crimes and sentenced to death. Cohn wrote in his autobiography that his influence led to Chief Prosecutor Saypol and Judge Irving Kaufman being appointed to the case, with Kaufman imposing the death penalty after Cohn's recommendation.

Historians have since challenged the pair's death penalty punishment, which has been criticised as "ill-advised", while some believe that Ethel Rosenberg was not guilty and that her trial was tainted by judicial misconduct.

Cohn is probably best known for being McCarthy's chief counsel. He came to be closely associated with McCarthyism, which is the practice of making accusations of subversion or treason without proper regard for evidence.

He also represented and mentored real estate developer and later President of the United States Donald Trump during his early business career.

In 1986, Cohn was disbarred from the Appellate Division of the New York State Supreme Court for unethical conduct after attempting to defraud a dying client by forcing the client to sign a will amendment leaving him his fortune.

Cohn died five weeks later from AIDS-related complications.

Bully, Coward, Victim: The Story of Roy Cohn will air on Sky Documentaries in August. If you’re looking for more to watch, check out our TV Guide.