A grand jury has refused to indict an 18-year-old accused of making a terrorist threat by posting a Facebook photo of a gunman shooting at a police car on the same day two officers were killed.

Authorities say Devon Coley posted symbols showing a gun pointed at an officer's head and a caption with his local precinct's number and the word "next."

On Dec. 20, two police officers were shot in their patrol car by a man who vowed online to kill "pigs." The suspect posted a series of online threats before the shooting.

The Brooklyn district attorney's office says Coley was being held without bail Friday. He still faces weapon possession and assault charges in separate cases.

The grand jury's decision was issued Thursday.