CHICAGO — Chicago officials on Friday released hundreds of videos and other investigative materials from 101 cases in which police officers fired their weapons or otherwise used force against civilians — a remarkable turnaround for an administration that fought last year not to release a video showing an officer fatally shooting a teenager as he lay sprawled on the ground.

Some of the Police Department’s critics hailed the release by Chicago’s Independent Police Review Authority, which investigates claims of misconduct and excessive force, as a watershed moment for a city whose police and political culture have a long history of secrecy and obfuscation. Chicago officials refused to release a video showing Officer Jason Van Dyke, who is white, shooting 17-year-old Laquan McDonald, who was black, 16 times, until a judge’s order forced the city to make it public last November, more than a year later. Officer Van Dyke was charged with murder.

“This is a significant step towards transparency in Chicago,” said Craig B. Futterman, a University of Chicago law professor who directs a civil rights and police accountability project at the law school. “We’ve had decades of the code of silence and a lack of police accountability and institutional denial. The real test is, what does the new normal look like going forward?”

But he noted that the city had changed its practices only under tremendous pressure, and argued that the change did not go far enough, still allowing too much time to pass before evidence is released.