Actor Benedict Cumberbatch has been linked to a dark family mystery worthy of an episode of his hit drama Sherlock after researchers at a British genealogy website discovered one of his ancestors was tried for murder at the age of 14.

The star's great-great maternal uncle Henry Ventham was accused of killing his friend Frederick Betteridge following an alleged argument in the early 1890s, and his trial became known in Hampshire, England as The Romsey Stabbing Case.

The facts of the drama have been unearthed by experts at family history website findmypast.co.uk, who traced the history of the case from the pages of local newspaper the Hampshire Advertiser.

Ventham and an eye witness claimed Betteridge suddenly charged at the accused and fell on a knife he was carrying while blackberry picking. A jury accepted that account and Ventham was found not guilty of murder and manslaughter, reports the Daily Mail.

And it appears The Romsey Stabbing Case is not the only part of Cumberbatch's past he'd like to forget about - according to the website researchers, his fifth great-grandfather, Abraham Cumberbatch, was a slave owner who ran a sugar plantation in Barbados.