FERGUSON, Mo. — Audio of police radio communications and video from surveillance cameras at the Ferguson Police Department offer new details from the day that Michael Brown, an unarmed black teenager, was shot dead by a white police officer in August.

As the region waits tensely for a grand jury to decide whether to indict the officer, Darren Wilson, in the shooting, the new disclosures gave yet another glimpse of the complicated and unusually abundant information that the jurors may be sifting through.

The audio and video were published on Friday by the St. Louis Post-Dispatch.

The police radio communications, including remarks by Officer Wilson, reveal that the encounter with Mr. Brown on Aug. 9 was brief — less than 90 seconds from start to finish. Though the time was short, questions remain about the encounter: Were Mr. Brown’s hands raised in the air in a motion of surrender when he was shot, as some witnesses have said? Was Officer Wilson punched and scratched in a struggle with Mr. Brown, as he has told the authorities? Did Officer Wilson view Mr. Brown as a suspect in a theft that had just occurred at a store?