Why has Maryland court trial footage of 'Serial' subject Adnan Syed rarely been broadcast?

HBO aired Sunday the first episode of its four-part documentary series “The Case Against Adnan Syed,” which includes rarely seen footage from the Baltimore County man’s 1999 trial for the killing of 18-year-old Hae Min Lee.

Here’s why Syed’s trial footage is not usually available to the public:

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Source: Sun County