Authorities now are actively looking for the man shown in surveillance video pouring or spilling liquid mercury onto the platform of the Pershing Square Metro station the night of Dec. 22. LATimes.com:

When it happened, officials quickly labeled it a harmless accident. But now, the county's joint terrorism task force has launched an investigation and is trying to find the man.

About 10:45 p.m. on Dec. 22, a man is shown crouching and appearing to drop something on the edge of subway platform. The man then reaches for an MTA intercom and tells a worker, "I spilled mercury," according to law enforcement officials, before boarding a subway train.

But in what officials admit was a breakdown in procedure, MTA workers didn't immediately clear out the area — or notify law enforcement or the fire department. Hazmat crews didn't respond to the scene until 7:15 a.m. the next morning — eight hours later.

See the video at the Times site.