The white Chicago policeman charged with murdering a black teenager he shot 16 times spent his first full day in custody on Wednesday in a jail hospital ward, as calm prevailed in a city braced for civil unrest over new video footage of the slaying.

Protests were mostly small and peaceful on Tuesday and Wednesday following the release of a graphic clip showing 17-year-old Laquan McDonald being gunned down in the middle of a street on Oct. 20, 2014, as he was walking away from police who had confronted him.

The tape, recorded from a dashboard-mounted camera in one of several patrol cars arriving on the scene, was made public on Tuesday under court order hours after the officer who fired the fatal volley of gunshots, Jason Van Dyke, was charged with first-degree murder.

Investigation of the case comes amid a national debate on race and police tactics sparked by a series of high-profile killings of unarmed black men at the hands of mainly white law enforcement in several US cities in the past two years, leading to widespread demonstrations and some violent unrest.

Late on Wednesday, the Chicago Tribune newspaper reported it had exclusively obtained video footage from the dashboard cameras of five police vehicles that were on the scene.

Those tapes include the one widely shown on Tuesday, which provides the most complete coverage of the shooting released to date. There is also footage taken from four other squad cars, including Van Dyke's vehicle, that were on the scene, the Tribune said.

None of those four tapes show the moment McDonald was shot.