Chemical weapons. U.N. taps special labs to investigate Syrian attack.

The U.N. investigators who traveled to Syria last week to probe an apparent chemical attack have turned their samples over to a specialized network of laboratories that can look for evidence of the weapons. Research advances since the last major chemical attacks in the 1980s and 1990s are enabling researchers to find evidence of such attacks in soil, clothing, and blood and urine samples days and even weeks after the event.