If your convict ancestor was a British citizen, a wealth of resources awaits you. These include the proceedings of the Old Bailey, 1674 to 1913, covering nearly 200,000 trials in London’s central criminal court.

The UK National Archives catalog lists a collection of petitions for clemency, wherein might be a letter your ancestor wrote to the judge; its Documents Online collection includes Victorian prisoners photos.

For a quick way to identify criminal ancestors in the UK, go to the archives’ catalog search. Enter a name (or just a surname) in the Word or Phrase box and type HO 47 in the Department or Series Code field. That restricts your search to a series of judges’ reports on criminals, spanning 1783 to 1830. Hits will give you a quick summary of why your ancestor was in hot water (“Report of Francis Buller on John Waltho, farmer, convicted at the last Staffordshire Assizes, for stealing 3 sheep, property of William Hanson, from Kings Bromley Common during the first week in October 1785 … ”); the original documents are in the archives in Kew.

For more on catching criminals in the UK’s archives, see Sources for Convicts and Prisoners: Domestic Records Information 88.

Descendants of Scottish scofflaws needn’t feel left out. Check the lively (yes, really) site for Inverary Jail, where you can search records of more than 4,300 prisoners—including those who were ultimately transported.