By Scott Malone

CLAYTON, Mo., Nov 17 (Reuters) - Several dozen demonstrators took to the streets Monday in Clayton, Missouri, where a grand jury is determining whether to file criminal charges against a white police officer who shot and killed an unarmed black teen in August.

Protesters expressed anger that, 101 days after 18-year-old Michael Brown was shot and killed in Ferguson, Missouri, it was still unclear what will happen to the officer, Darren Wilson.

The St. Louis area is on edge before the decision, which could come any day, and if no charges are brought, many fear a repeat of the sometimes violent protests that rocked Ferguson three months ago.

"We want an indictment. The cops don't like it," the group chanted on a day when the temperature was well below freezing as they marched outside the Clayton County courthouse where the grand jury is sitting.

"Something about the way Mike Brown was killed started a fire in me that I can't ignore," said one of the demonstration's organizers, Dhorbua Shakur, 24.

He said he had little sympathy for area residents who are tired of the demonstrations, which left some businesses in Ferguson burned out.

"They can turn this off and on with a TV screen. But this is my reality. This is my life," Shakur said.

Some area schools have told parents they will dismiss students early when the decisions comes and many businesses near the stretch of downtown that saw the worst rioting after Brown's killing have boarded up their windows in as a protective move.

Officials have said the grand jury's decision is likely to come this month.

Video and audio published over the weekend by the St. Louis Post-Dispatch showed Wilson leaving the police station and returning to it hours after the Aug. 9 shooting.

There are conflicting accounts of what happened, with some witnesses saying Brown had his hands up in surrender when he was shot and others describing a physical altercation between Brown and Wilson.

Protest organizers planned to demonstrate at the Ferguson Police Department when the grand jury's decision comes back, and later at the county courthouse in Clayton. (Editing by Doina Chiacu)