Authorities in Atlanta are grimly piecing together what they know about Mark O. Barton, the 44-year-old father, investor and former murder suspect who walked into two Atlanta brokerages and killed nine people.

Some questions may never be answered: Barton sped away after the shooting rampage, driving to a suburb where he killed himself Thursday evening as police closed in. Authorities later said he had killed his wife and two children before committing one of the worst workplace massacres in the nation’s history.

Twelve people were injured, some by bullets and others by their frantic attempts to avoid the killer. Seven remained in critical condition today.

Guest:

• Paul Barrett, Wall Street Journal.