Orlando shooting follows other incidents, including Ft. Hood. But the trend is downward in recent years due to new workplace protections and policies.
Authorities issued warrants to raid the apartment of Raymond Clark III and take a DNA sample. He worked in the building where graduate student Annie Le's body was found.
Annie Le, a doctoral student in pharmacology, was due to be married Sunday. Police questioned a professor of hers who canceled class around the time she disappeared.