Dozens of former officials have spoken to the BBC about their role enforcing the brutality of the Assad regime – including a man who said he tortured detainees, then defected in 2012.

The rare first-hand testimony forms part of a BBC investigation into Syria’s notorious prisons under its former president, Bashar al-Assad, who was overthrown last December.

A UN report earlier this year said detentions and torture under the former regime constitute crimes against humanity.

Syrian human rights groups estimate that around 100,000 people disappeared under Assad’s 24-year rule.

The BBC agreed to conceal the identities of the former regime officials it spoke to on account of the value of their testimonies.

In the UK, you can watch the full documentary, Surviving Syria’s Prisons, here.