Why is Rudy Giuliani being indicted alongside Donald Trump?

He was once known as "America's mayor" for his leading role helping New York City in the aftermath of the 9/11 terror attacks. Now Rudy Giuliani has been indicted alongside Donald Trump for his alleged role interfering in the 2020 presidential election.

The BBC's Anthony Zurcher explains what the charges are, and how the former Republican presidential candidate is involved.