Inside Syria's prisons, where an estimated 17,723 have died since 2011

[Rob L 3,811]

The beatings began as soon as they were arrested, and they continued at a "welcome party" at the detention center.

That's the term dozens of Syrian detainees used to describe treatment at the hands of government forces upon arriving at one of Syria's prisons.

A group of guards usually carried out the beatings, often with tools such as silicone bars and hoses, to punish prisoners for their perceived opposition to Bashar al-Assad's regime, according to a new report from Amnesty International.

The punishment was a sign of more torture to come.

http://www.cnn.com/2016/08/17/middleeast/amnesty-report-syria-torture-deaths/index.html

The detainees' experiences are detailed in the new report, which estimates that 17,723 people have died in custody in Syria since the crisis began in March 2011 -- an average rate of more than 300 deaths each month.

ICRC spokesman: Aleppo suffering has been enormous 01:49

The estimate is based on reports from four organizations investigating deaths in Syria from March 15, 2011, to December, 31, 2015. From those cases, the Human Rights Data Analysis Group identified 12,270 cases with sufficient information to confirm the person was killed in detention. Using a statistical method to estimate how many victims they do not yet know about, the group came up with 17,723 cases.

But the group believes that's an underestimate, based on criteria used to define a killing in detention. CNN has attempted to reach out to the Syrian government for comment.