14/08/2014 16:55 BST | Updated 22/05/2015 10:12 BST

Murder Mystery In Sherlock Star Benedict Cumberbatch's Family

It's a mystery that could have come out of a Victorian crime novel... but it's from the real-life past of Sherlock star Benedict Cumberbatch.

The actor has an ancestor who was caught up in a child murder case that might have tested the powers of the famous fictional detective.

A historian uncovered the grim tale while investigating the maternal branch of Benedict's family tree.

The relative, Henry Ventham, was alleged to have knifed a 12-year-old friend after they rowed while picking nuts.

The victim claimed on his deathbed the act was deliberate – but a witness said the boy fell on Henry's knife. The 1893 trial in Hampshire cleared Benedict's great great uncle of murder.

Benedict, 37, is known for having a distinguished paternal line of merchants and adventurers, but the new research was described as 'startling'.

Debra Chatfield, from, said: "It seems there was a dark horse in Benedict's family tree."