FERGUSON Mo. (Reuters) - Activists protesting the fatal shooting in August of an unarmed black teen by a white policeman expressed anger on Saturday after the city's police chief told local media the officer could return to work if a grand jury does not to charge him criminally.

The St. Louis suburb of Ferguson, which saw weeks of sometimes violent protests following the Aug. 9 shooting, is on edge as a grand jury decides whether the officer, Darren Wilson, will face charges for the shooting of Michael Brown.

Wilson would likely be fired if he is indicted, but could immediately return to duty if he is not, Ferguson Police Chief Tom Jackson told St. Louis broadcaster KSDK, adding that he had not spoken with Wilson to know if he wanted to rejoin the department.

A Ferguson police spokesman did not respond to a request for comment.

Reverend Osagyego Sekou, a leader of the Ferguson protesters, said a return to duty by Wilson would sadden and anger some in the community. Sekou has been training protesters in nonviolent civil disobedience techniques ahead of the grand jury's report, which could come any day.

"It's part of a pattern of police impunity," Sekou said. "They can do whatever they want with no consequences."

A group of a couple dozen protesters, many wearing the Guy Fawkes masks adopted by the Anonymous movement, gathered outside the Ferguson police department on Saturday, holding their hands up in surrender, a gesture that some witnesses have said Brown was making at the time of the shooting.

There have been conflicting witness accounts of the shooting and others have described it as a struggle between Brown and Wilson.

Many in the St. Louis area fear that another wave of rioting could follow the grand jury's report, particularly if it decides not to bring criminal charges.

One area school district has said it plans to release students early if the decision comes on a weekday, saying that the St. Louis Country prosecutor's office has promised to give it an early warning of the decision.

The prosecutor's office has not commented on whether it will offer such an early heads-up to local leaders.

(Reporting by Scott Malone. Editing by Andre Grenon)

Activists in Ferguson dismayed officer in shooting may return work