Daniel Radcliffe was reduced to tears while reading the suicide note of his great-grandfather.
The actor was handed the final letter of his desperate ancestor on BBC show Who Do You Think You Are?, which airs on Monday night.
His great-grandfather was embroiled in bankruptcy following a potentially fraudulent heist and insurance claim at his Hatton Garden jewellery business.
Radcliffe tearfully read the businessman's suicide note and wished he could reach back in time to comfort his great-grandfather Samuel Gershon.
He had become the focus of intense publicity in the build-up to his death, and left a note expressing intense love for his wife.
She anglicised her name following the scandal in a bid to protect her family from the press.
Radcliffe said: "You just want to sort of reach into the past and just go like, 'whatever you're going through, you have so much to offer the people that are around you still'."
Crying at the content of the note, he added: "It's so sad. Everything in one part of his life was great.
"I worry a lot. I sort of have a lot of anxiety and can really get lost in that sometimes.
"It's sad to think of it getting so bad for him that he had to do this."
His great-grandfather was under suspicion over suspected fraudulent claims made following the robbery of a safe.
However, the police documents revealed the roots of this suspicion was due to the fact: "That he is a Jew. And the Jews are so frequently responsible for the bringing down of their own businesses."
Radcliffe expressed his pity for his ancestor, and said he found the language used to described him as "jarring". The insurance claim following the robbery was ultimately settled.
The actor also learned about the First World War experiences of his great-great uncle on his father's side of the family.
He was killed by artillery, leaving behind a wife who was passionately in love with him.
Radcliffe was deeply affected by the story of love being destroyed by war, but was relieved that the pair were "able to be a young couple for a little while".
He added: "I can't be sad about it, because everyone was really loved. Ultimately that means that the time they had on Earth, even if it ended really prematurely and sadly, was worth having."
Who Do You Think You Are? airs on BBC One at 9pm.